Do the police have the obligation to exchange themselves for hostages?

I believe that a ship’s crew should throw themselves overboard to save the captain in cases where a pod of killer whales attack.

I’ve never thought about a hostage situation, though. Mostly because that isn’t something whales do. 

A lot of cops are total p*ssies who cleverly go on medical leave if they get scratched while  kicking the sh*t  out of a civilian so they can make it look like it was the other person’s fault. LOL LOL. Works every time

I really don't think they teach that.