Stanley cut his way through many floors of the building, making his way toward the top.
On each floor, he would start by destroying the various cameras while the time was slowed down and then move onto the people that were in there.
His guns killed the ones far away, while his sword killed the ones that were closed. Before the ones that wee attacked even realized they were attacked, most of them all died.
A person or two would survive either because of some shield they had on, or some powers that made it hard to Stanley to kill them. In those instances, Stanley simply knocked them out and moved on.
The most difficult person to take care of had been on the 4th floor where he came across a pregnant woman. He had known about her before even coming and knew just how much of a horrible person she was.