So who shot first?

Were there only the two officers on scene? Because the other guys has his gun out, but at low ready. And he takes off when you hear the shots, so it doesn't seem like he fired either.

So unless there were other cops there, seems pretty likely the shots were from the car. Seems weird though, as at least from this angle there's only the one window down, no windows break, and you can't see any gun or flashes from the open window. So not sure what's going on, exactly.