Who is more at fault, the officer or the driver? 

This whole video is bizarre. A woman and her van full of kids is pulled over, she speeds away, gets pulled over again...then chaos really ensues.

I don't think either are right in their actions, but was what the police did necessary?

Yes, the driver was totally in the wrong for speeding away, but why does the other officer open fire? I've watched enough TV to know that you aren't supposed to shoot unless the suspects have weapons as well. I mean, he shot at a minivan full of kids!