If an ambulance is on its way to save someone, and it runs someone over, does it stop to help them?

I don't think they are allowed to help them. They would have to call for another ambulance to come to the scene. Things with the emergency services are a bit messed up. There was an incident on a bus I was on once. The incident happened when we were stopped right outside a police station but nobody in the police station could help the bus driver had to actually phone 999 for somebody to come out the front door ha ha madness.