Gun drawn, Colossus entered simultaneously with Shadowcat, hoping that he would distract attention from his smaller teammate, and began firing. The Russian had far less internal conflict than Kitty, which was saying quite a lot. These people needed help, and this was the way to do it. If the sick wanted to bite you; cure them from a distance. However, a 'distance' wasn't quite the case on this particular day...
From atop opposite facing filing cabinets, several Darkseekers leapt toward he and Kitty's heads, and as Piotr's arm raised to deflect the attack on his own person, his flesh began transforming over to metal. Had he anticipated a sneak attack, he might've already been armored up. The infected human landed with their teeth sunk into his flesh and as his armor formed, the Darkseeker fell to the ground momentarily, then began clawing at the bottom of his pants. He lowered the weapon and shot once, then raised it again to assist Kitty. "Net!" he growled in dismay. Their scuffle had drawn the attention of the rest of the lurkers. The dozen had quickly turned into a hungry, hoarding hundred. He moved to the side (Kitty's side) and lowered himself to one knee, then began firing into the oncoming crowd. The doorway was left open for their teammates to enter, or at least get as many hits as possible.