173 had been moving quite a bit through the town, snapped a few necks, and became a statue for a while. It had seen the fire start just now, if I fire started, it meant people, if there were people, it meant necks, if there were necks, it meant snapping. It quickly moved and 'ran' to where the fire was. It saw a crazy man laughing into the sky an on fire, then cartwheel out of the tent. it followed, and saw more people. He ran forward, about to snap Jack's neck, when a girl frozen in place apparently had seen it, so he immediately froze in place instinctively.
(( jst incase the actual creepypasta page for SCP-173 doesn't say how fast he moves, he moves about 35 mph when unseen. ))