It seemed like more of a screwed up execution.
He wouldn’t surrender (til he crashed).
They probably starting firing the instant he slid into and knocked aside the FBI guy.
He might have reached for a gun (did they in fact find one ?) But that was after he got out and walked a ways with hands up. Then he put his hand out or up again, then reached inwards again.
They fired again until he dropped.
It seemed to be an event that had an inescapable conclusion.