Learning more about Policemen

Conversation went something like this:
Regan:  Mommy, is that a police car?
Me: Yes, good job.
Regan:  Who is in the police car?
Me:  Hopefully a policeman (I didn’t say woman but I was just thinking along the lines of someone official and real).
Regan:  What do policemen do?
Me:  Well, they help if there is an accident, they pull you [...]