It all happened so fast in Vin's eyes. A battle had just taken place between gang members and three Jedi... or people who just simply liked the feel of a Lightsaber in their grasp. Vin especially noted aside from the two young girls was a familiar looking man. He saw him at the Jedi Temple a few times, and had recently heard reports he left the temple.
As soon as the three fled, Vin wondered if he should follow; intrigued with the idea whether he should help Jack.
Vin fled the scene as well, spotting the group and followed them in the shadows without their detection. He had just managed to see from a distance Jack disarming a thug and shot him with his own blaster.