# 36 leading Security and Investigations companies in California

Tamtam tracks 36 Security and Investigations companies headquartered in California. This list ranks all of them by number of employees on LinkedIn, led by Inter-Con Security, Universal Services of America and Security Industry Specialists. Their median headcount is 307. Half of them were founded in 1999 or later. The most common headquarters are Los Angeles (4), Culver City (2) and Fresno (2).

The Security and Investigations companies in California listed here are primarily mid-sized to large firms, many with national or international operations. They offer a broad spectrum of services, from physical security and executive protection to advanced security screening solutions and integrated systems. Companies like Inter-Con Security provide comprehensive security services to government agencies and businesses, while Rapiscan Systems specializes in threat detection products.

A notable pattern among these companies is their concentration in Southern California, particularly in the Los Angeles metropolitan area. For example, Security Industry Specialists, AGS Protect, and Professional Security Consultants, Inc. are all headquartered in or near Los Angeles. This regional clustering suggests a significant hub for security and investigations expertise in the area.

🇺🇸 California · 36 companies · Updated Nov 14, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [Inter-Con Security](https://www.tamtam.ai/c/inter-con-security) (icsecurity.com)<br>A multinational private security company providing comprehensive security services, risk analysis, and management to government agencies, businesses, and individuals globally | Security and Investigations | 🇺🇸 Pasadena | 5,126 | 1973 |
| 2 | [Universal Services of America](https://www.tamtam.ai/c/universal-services-of-america) (aus.com)<br>A leading security services company formed from the merger of AlliedBarton Security Services and Universal Services of America in 2016 | Security and Investigations | 🇺🇸 Santa Ana | 3,076 |  |
| 3 | [Security Industry Specialists](https://www.tamtam.ai/c/security-industry-specialists) (sis.us)<br>Leader in security services for Fortune 500 companies, international events, and celebrities Known for innovative solutions, transparent approach, and unique corporate culture | Security and Investigations | 🇺🇸 Culver City | 2,654 | 1999 |
| 4 | [Rapiscan Systems](https://www.tamtam.ai/c/rapiscan-systems) (rapiscansystems.com)<br>A global leader in security screening solutions, providing cutting-edge products and services for threat detection and operational efficiency worldwide | Security and Investigations | 🇺🇸 Torrance | 1,472 | 1993 |
| 5 | [Andrews International](https://www.tamtam.ai/c/andrews-international) (andrewsinternational.com)<br>A global security company with expertise in government services, consulting, investigations, and specialized security solutions through strategic partnerships and experienced professionals | Security and Investigations | 🇺🇸 Burbank | 1,082 | 1988 |
| 6 | [American Guard Services, Inc.](https://www.tamtam.ai/c/american-guard-services-inc) (americanguardservices.com)<br>An accredited security protection firm specializing in Cruise Ship Passenger Terminal Operations, with nationwide locations and a focus on training staff in industry regulations | Security and Investigations | 🇺🇸 Gardena | 867 | 1997 |
| 7 | [Professional Security Consultants, Inc.](https://www.tamtam.ai/c/professional-security-consultants-inc) (pscsite.com)<br>Provider of security guard services, patrol, investigations, executive protection, and web-based incident management software with national and international operations | Security and Investigations | 🇺🇸 Los Angeles | 846 | 1985 |
| 8 | [Bay Alarm Company](https://www.tamtam.ai/c/bay-alarm-company) (bayalarm.com)<br>A family-owned national security company with a focus on customer safety, employee development, community involvement, and delivering the best service possible | Security and Investigations | 🇺🇸 Concord | 844 | 1946 |
| 9 | [AGS Protect](https://www.tamtam.ai/c/ags-protect) (agsprotect.com)<br>A reliable security guard service known for quality, efficiency, and professionalism Dedicated team exceeding expectations to ensure full satisfaction | Security and Investigations | 🇺🇸 Culver City | 573 | 2017 |
| 10 | [Elite Security & Staffing](https://www.tamtam.ai/c/elite-security-and-staffing) (elitesecuritystaffing.com)<br>Company provides customized security solutions and nationwide deployment of security guards for events, facilities, and various industries with a focus on safety and satisfaction | Security and Investigations | 🇺🇸 San Diego | 480 | 1995 |
| 11 | [Pelco](https://www.tamtam.ai/c/pelco) (pelco.com)<br>This company specializes in developing and manufacturing open IP video security systems, cameras, video management systems, displays, and accessories with high customer service | Security and Investigations | 🇺🇸 Fresno | 452 |  |
| 12 | [Pavion, Formerly RFI](https://www.tamtam.ai/c/pavion-formerly-rfi) (pavion.com)<br>A leading security integrator specializing in design, installation, and maintenance of integrated systems for various industries, providing 24x7 monitoring and managed services | Security and Investigations | 🇺🇸 San Jose | 406 | 1979 |
| 13 | [United Security Services](https://www.tamtam.ai/c/united-security-services) (unitedweguard.com)<br>Leading security consulting company providing strategic onsite security solutions with professional guard and patrol services, utilizing sophisticated technology for a safe environment | Security and Investigations | 🇺🇸 Corona | 404 | 1999 |
| 14 | [Security Guard App](https://www.tamtam.ai/c/security-guard-app) (securityguard.app)<br>The company offers a Security Guard Web App and Mobile App for guards, security guard companies, and clients to manage security operations | Security and Investigations | 🇺🇸 San Jose | 332 | 2018 |
| 15 | [GSG Protective Services](https://www.tamtam.ai/c/gsg-protective-services) (gsgprotective.com)<br>A full-service provider of quality security services specializing in investigations, physical security, technology, training, and consulting for various sectors and environments | Security and Investigations | 🇺🇸 Lawndale | 325 | 2000 |
| 16 | [Guardian Security](https://www.tamtam.ai/c/guardian-security) (guardian-security.net)<br>Provider of security alarm systems and CCTV surveillance camera systems for homes and businesses in Southern California, with value pricing, quality service, and timely installation | Security and Investigations | 🇺🇸 Los Angeles | 316 |  |
| 17 | [Surefox North America](https://www.tamtam.ai/c/surefox-north-america) (surefox.com)<br>We specialize in providing custom security solutions with a focus on supporting military veterans and seamlessly integrating into our clients' lives | Security and Investigations | 🇺🇸 Sunnyvale | 315 | 2016 |
| 18 | [NAVCO](https://www.tamtam.ai/c/navco) (navco.com)<br>A national electronic security integrator offering video recording, alarms, biometric identification, access control, system design, remote monitoring, and equipment rental services | Security and Investigations | 🇺🇸 Orange | 307 | 1971 |
| 19 | [Northland Controls](https://www.tamtam.ai/c/northland-controls) (northlandcontrols.com)<br>Global physical security systems integrator specializing in design, installation, and management for demanding organizations worldwide, driven by core values and operational expertise | Security and Investigations | 🇺🇸 Fremont | 284 | 1982 |
| 20 | [C.I. Security Services (CISS)](https://www.tamtam.ai/c/c-i-security-services-ciss) (cisssecurity.business.site)<br>A security company based in California, offering premium security services for commercial and private properties as well as event security with a skilled team | Security and Investigations | 🇺🇸 Glendale | 202 | 1992 |
| 21 | [Skyline Smart Home](https://www.tamtam.ai/c/skyline-smart-home) (skylinesecurity.com)<br>A leading distribution channel for Brinks Home Security, offering national sales and installations of security and smart home solutions | Security and Investigations | 🇺🇸 Downey | 183 | 1999 |
| 22 | [Platinum Security Inc.](https://www.tamtam.ai/c/platinum-security-inc) (platinumsecurity.com)<br>A customer-focused security company with over 20 years of experience, offering tailored security programs for Fortune 500 companies to homeowners' associations | Security and Investigations | 🇺🇸 Los Angeles | 182 | 1997 |
| 23 | [Absolute International Security](https://www.tamtam.ai/c/absolute-international-security) (absolutesecurityintl.com)<br>Absolute Security International provides licensed private security services, surveillance, training, threat assessment, investigation, and mediation with over 115 years of industry experience in Southern California | Security and Investigations | 🇺🇸 Irwindale | 175 | 2008 |
| 24 | [Superior Protection Services](https://www.tamtam.ai/c/superior-protection-services) (superiorprotect.com)<br>Join our exceptional team to be a part of something great | Security and Investigations | 🇺🇸 Commerce | 161 | 1994 |
| 25 | [SSD Alarm](https://www.tamtam.ai/c/ssd-alarm) (ssdalarm.com)<br>A family-owned security and fire alarm company founded in 1968, offering advanced system solutions, UL listed monitoring, and industry-leading products/services | Security and Investigations | 🇺🇸 Anaheim | 160 |  |
| 26 | [Hikvision USA](https://www.tamtam.ai/c/hikvision-usa) (hikvision.com)<br>A global leader in security technology, offering a wide range of products and solutions for various industries with a focus on quality, safety, and cybersecurity | Security and Investigations | 🇺🇸 Industry | 158 | 2001 |
| 27 | [ZBeta, Inc.](https://www.tamtam.ai/c/zbeta-inc) (zbeta.com)<br>A top-tier firm specializing in strategic physical security design and managed services, aimed at transforming security into organizational excellence | Security and Investigations | 🇺🇸 Larkspur | 157 | 2006 |
| 28 | [AmeriGuard Security Services, Inc.](https://www.tamtam.ai/c/ameriguard-security-services-inc) (ameriguardsecurity.com)<br>A Fresno-based private security contractor offering armed/unarmed officers, vehicle patrols, alarm response, security camera installation, background checks, LiveScan fingerprinting, and more nationwide | Security and Investigations | 🇺🇸 Fresno | 154 | 2000 |
| 29 | [MPS Security & Protection](https://www.tamtam.ai/c/mps-security-and-protection) (security-mps.com)<br>A full-service security provider offering executive protection, residential security, access control, security patrols, loss prevention, fraud detection, and risk management services | Security and Investigations | 🇺🇸 Murrieta | 152 | 2003 |
| 30 | [Off Duty Officers, Inc.](https://www.tamtam.ai/c/off-duty-officers-inc) (offdutyofficers.com)<br>National security services provider specializing in off-duty law enforcement officers for workplace violence, executive protection, event security, and various other security needs | Security and Investigations | 🇺🇸 Vista | 152 | 1993 |
| 31 | [Alias Intelligence](https://www.tamtam.ai/c/alias-intelligence) (aliasintelligence.com)<br>A leading background investigations and due diligence company, offering comprehensive checks, asset searches, and business investigations to evaluate relationships, opportunities, and risk | Security and Investigations | 🇺🇸 Los Angeles | 149 | 2021 |
| 32 | [Alvarado](https://www.tamtam.ai/c/alvarado) (alvaradomfg.com)<br>A US-based company specializing in secured entry control, admission systems, queuing, and asset protection products, known for quality, reliability, and innovation | Security and Investigations | 🇺🇸 Chino | 147 | 1956 |
| 33 | [Spintly](https://www.tamtam.ai/c/spintly) (spintly.com)<br>Company providing easy and secure entry to modern workplaces with a smart access control system using smartphones, eliminating the need for wired infrastructure | Security and Investigations | 🇺🇸 Milpitas | 146 | 2018 |
| 34 | [TechReal Capital](https://www.tamtam.ai/c/techreal-capital) (techrealcapital.com)<br>Investment advisor registered with SEC, offering advisory services Past performance not indicative of future returns Investing involves risk | Security and Investigations | 🇺🇸 Sacramento | 17 | 2018 |
| 35 | [VAMO Digital](https://www.tamtam.ai/c/vamo-digital) (vamodigital.com)<br>A digital agency empowering professionals to boost profits with innovative solutions since 2010, combining tech and human expertise for growth | Security and Investigations | 🇺🇸 Gold River | 7 | 2010 |
| 36 | [ApolloShield Counter-Drone Systems](https://www.tamtam.ai/c/apolloshield-counter-drone-systems) (apolloshield.com)<br>Specializing in detecting and blocking unwanted drone intrusions, tracking down and arresting unauthorized operators, serving 25+ countries with expertise from Israel Defense Forces | Security and Investigations | 🇺🇸 Palo Alto | 4 | 2015 |

## How this list is built

Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 14, 2026.

## More company lists in California

- [The largest companies in California](https://www.tamtam.ai/l/largest-companies-california) (15,258)
- [Multinational companies in California](https://www.tamtam.ai/l/multinational-companies-california) (2,587)
- [SaaS companies in California](https://www.tamtam.ai/l/saas-companies-california) (1,854)
- [Software Development companies in California](https://www.tamtam.ai/l/software-development-companies-california) (1,649)
- [AI companies in California](https://www.tamtam.ai/l/ai-companies-california) (1,296)
- [Companies with in-house R&D in California](https://www.tamtam.ai/l/r-and-d-companies-california) (1,272)
- [Manufacturers in California](https://www.tamtam.ai/l/manufacturers-california) (1,065)
- [Hardware manufacturers in California](https://www.tamtam.ai/l/hardware-companies-california) (984)
- [IT Services and IT Consulting companies in California](https://www.tamtam.ai/l/it-services-and-it-consulting-companies-california) (968)
- [Education providers in California](https://www.tamtam.ai/l/education-companies-california-united-states) (950)
- [Subscription businesses in California](https://www.tamtam.ai/l/subscription-businesses-california) (939)
- [Venture capital and private equity firms in California](https://www.tamtam.ai/l/vc-and-private-equity-firms-california) (917)
- [Professional services firms in California](https://www.tamtam.ai/l/professional-services-firms-california) (880)
- [Companies with a mobile app in California](https://www.tamtam.ai/l/companies-with-mobile-app-california) (827)
- [Retail chains in California](https://www.tamtam.ai/l/retail-chains-california) (802)
- [IT services companies in California](https://www.tamtam.ai/l/it-services-companies-california) (796)
- [Venture Capital and Private Equity Principals companies in California](https://www.tamtam.ai/l/venture-capital-and-private-equity-principals-companies-california) (731)
- [Financial services firms in California](https://www.tamtam.ai/l/financial-services-firms-california) (711)
- [Financial Services companies in California](https://www.tamtam.ai/l/financial-services-companies-california) (642)
- [Healthcare providers in California](https://www.tamtam.ai/l/healthcare-providers-california) (569)
- [AI-native companies in California](https://www.tamtam.ai/l/ai-native-companies-california) (561)
- [Hospitals and Health Care companies in California](https://www.tamtam.ai/l/hospitals-and-health-care-companies-california) (555)
- [Consulting firms in California](https://www.tamtam.ai/l/consulting-firms-california) (551)
- [Public sector organisations in California](https://www.tamtam.ai/l/public-sector-organisations-california) (536)

## The same list elsewhere in United States

- [Security and Investigations companies in the United States](https://www.tamtam.ai/l/security-and-investigations-companies-united-states) (288)
- [Security and Investigations companies in New York State](https://www.tamtam.ai/l/security-and-investigations-companies-new-york-state) (47)
- [Security and Investigations companies in Florida](https://www.tamtam.ai/l/security-and-investigations-companies-florida) (25)
- [Security and Investigations companies in New York](https://www.tamtam.ai/l/security-and-investigations-companies-new-york) (25)

## The same list elsewhere

- [Security and Investigations companies in North America](https://www.tamtam.ai/l/security-and-investigations-companies-in-north-america) (352)

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Source: https://www.tamtam.ai/l/security-and-investigations-companies-california