In some places they have policies for cops not to engage in high speed chases under some circumstances because innocent people get hurt.
This person was swerving everywhere, running red light intersections and sent his trailer into another car.
This guy was such a risk they had to end him from the looks of it because to just let him go at that moment appeared to be a great big public risk within itself.
Someone said shoot out the tires. That is not easy to do and would be where the public could get killed, so I am not always for shooting out tires either.