The mutagen spread through Area 51 rapidly, infecting many of its inhabitants. The security forces happened to fall victim to the virus before they could control it, and the workers were left without any protection.
Mutant security forces wear torn black clothing, different from the usual Spec4 uniforms.
Mutant security guards are extremely aggressive, often charging at their prey relentlessly.The mutant security guards maintain their cognitive skills to operate firearms in a rudimentary manner. They carry XM-32 Assault Rifles with one hand, but carry M-170 Shotguns at their hip with both hands. Furthermore, mutant security guards may dodge gunfire. This may be because they still retain their combative instincts.
Mutant security guards have 50 health. They often drop Frag Grenades when killed.
Mutant security guards often carry the XM-32 Assault Rifle and the M-170 Shotgun. When carrying the former, they can swipe with their left hand.
Mutant security forces are the primary enemy alongside mutant scientists for the first 1/4 of the game. After The Last Stand, mutant security guards show up only one more time, in Dr. Cray.