You reach the top of the stairs. The same flashing lights meet you on this level. You're still in the facility. A few feet down the hall a trail of bodies is scattered along the corridor. In the hands of the nearest body is a radio. It almost looks too damaged to use, but you can't all from this distance. He has a sizable hole in his chest. So do most of the corpses. The other direction is barred by a pile of shredded metal and twisted beams.

If you move through the bodies go to part 22
If you grab the radio go to part 23