Cops shooting at the wrong vehicle and killing the occupants would be manslaughter at worst; but the definitions of murder vary from state to state. If the occupants are just injured then it's even less severe of a crime.
Technically, manslaughter is not the same as premeditated, or first-degree, murder.
However, I think those police officers need to be taken off of active duty and placed under arrest until they can stand trial. Reckless cops have no business on the police force.