ROMAC is falling apart and Gabriel isn't going to let it fall without having a hand in it. Iman and Rush are probably somewhere upstairs, but he's going to start where he can make the most impact. He flies into a lower level and starts working his way down. There are people being kept here and he releases them as finds them, either by forcing the doors or shorting out the electronic locks.

He doesn't ask why they're imprisoned. He just gets them out.

When he goes down another level, the cells are there, but they're empty. Some are larger, some have clearly been improved and fortified. This is definitely where they are building the new angel cages. Where a level up he'd been working methodically, here Gabriel just starts pushing through walls. His cage had had it's source of power in the wall, and he doesn't want to miss anything.