Both at fault. Cop shouldn't have pulled out but the guy did randomly speed up and he was flying to move that car around. But they shouldn't have been street racing and that guy shouldn't have sped up. The other guy seemed to slow down a bit when the one guy sped up.
Cop was wrong but probably didn't realize how fast they were going and figured they would all stop in time and they would have if it wasn't for that one.
Stupidity by both imo