I think Dunbar is pretty much toast. They needed a quick reaction force as soon as the first bomb was triggered. If we take a quick survey, we can see how screwed they are.

Power cut to the elevators.
Lost control of the minigun.
The single set of stairs ( I think there is only one ) is now dominated by the opforce.
The third floor has the windows sealed.

The people on the Third floor would have to take back the stairs to go anywhere. Alternatively, they could try and suppress fire coming from stairs to try and open the elevator and climb the shaft. But, Puck will have to stay behind, because as soon as the suppressive fire stops, the mallers charge the shaft.

Puck with an M16 is way out gunned by the minigun, so he will be hard pressed to gain fire superiority. People that are higher in the tower may have access to open windows and the fire escape. But, if I was scratch, I would have the fire escape covered in case someone tries to rabbit.

The stairs and the fire escape are fatal funnels and will most likely be dominated by the mallers...

Go fast
Go hard
Go ugly, early...