An imp will spawn in; you’ll find a medkit and ammo in the top left corner of the room. There’ll be another z-sec to kill then you’ll find the door on the right is locked. Once you kill all the trites that spawn in, a couple of z-secs will enter and you’ll be able to go through the door. You’ll find a couple of zombies; check the dark corridor on the left for ammo and hidden armor, but be careful when you get the armor as a couple of imps will spawn in and then zombies, more imps and z-secs.
On the plus side, the lights will be on now so you can hoover up the previously hidden pick ups behind the pillars along the corridor. Go back to the room at the end and take the door on your left. There’s a zombie and more trites, once they’re done there’s a medkit in the dark corner next to the lift. Jump on the lift and hit the panel to descend, an imp and four maggots will spawn in at the bottom.