After you save wurm, go backwards but stay in the same tunnel. there are about 10 more SWATs that you have to fight. save your entry shotgun ammo for this (along with alot of focus) because they also all have shot guns and it's really hard to kill them. It took me a few tries. To minimize using shotgun ammo at the beggining of the level, use pistols to kill everyone up to the point where you get the flashlight, then use machine gun. after you get to the part of the tunnel where sparks tells you to follow the swats, follow them until you can just see one (stay on the upper level) and throw a offensive grenade or any kind you have. that will either wipe them all out or kill a few of them. if you go in and find them all dead, wait there until wurm's health dissapears, because there are people underground where wurm is and you also have to kill them. then wait for most of your focus and health to restore. There is also one of those red health restoring packs there. then follow the tunnel until you get to the end, where the swats are. do alot of focus running on the walls and such to avoid getting hit.