Sloan's experiments have created grotesque mutants, and you'll need to destroy their spawning points to prevent an endless horde. These spawners are typically large, pulsating organic masses that continuously generate smaller, fast-moving mutant creatures. They are often found in cavernous or heavily contaminated areas.
To destroy a spawner, you'll usually need to shoot its glowing weak points or use explosives. The challenge comes from the constant stream of mutants it produces. Prioritize taking out the spawner quickly. Use shotguns or automatic weapons for crowd control against the smaller mutants. Grenades or C4 can be highly effective against the spawner itself. After destroying one spawner, you'll likely need to locate and destroy several more in the vicinity. Be mindful of your surroundings, as these areas can be claustrophobic and disorienting.