I'm reluctant to call out the cop's actions at this point. There could have been a threat issued by the kid who kept getting out of the van and heading at the cop.
They have radios, they have more cops up the road, they have spike strips and so on. Absolutely no legitimate reason to shoot.
Everybody there goofed up big time but shooting at a fleeing car occupied by innocent people, when it is not in any way an immediate threat, can not be condoned.