They rushed through the open spaces in the frame of the building, pushing past each other and even trading blows in their haste to get to the humans inside. For a few moments it seemed like they were going to get stuck on eachother, and their progress inside the room halted momentarily. Catching the humans inside off guard, the move bought them a few seconds without attack as the humans took the time to finish reloading their weapons and ready them once again.
By the time they started firing once more, it was almost too late for it to even matter. While they were able to drop some of the aliens, there were always more to replace them. And in the small space that they had to work with, this represented a significant problem for them.