The commandoes kept moving floor to floor, killing everyone they encountered whether they were armed or not. As Chrissy's apartment was on an upper floor, the commandoes from the roof were going to reach them first. The elevators were still working and running, as employees used them to flee.
The lobby was a deathtrap though, the floor mined and machinegun emplacements near all the exits to cut down anyone emerging from the elevators or stairwell. The police were not coming...they had been paid off to stay away. All communications were being jammed except for a local radio frequency that was encrypted and being used by the commandoes.