Exit onto this floor but don’t enter the hallway with the yellow glow. Steer left and then left again while taking down these guards. Watch for the wall to open with even more guards as you turn the corner and enter the room that looks over where you entered Level 2. Take a look around up here since they’ll be some goodies to snag as well (armor shards, bullets and health) and then carefully drop back down to get the health on top of the crate. Exit this room just like you did before, and enter the elevator again.