Were the police that refused to let the people off of the bridge during the Katrina disaster ever punished?
I don't think so. I haven't heard anything about the Federal lawsuit being settled. The town itself supported the police's actions, so the only way I would see them being punished would be in conjunction with the lawsuit.
how were they punished?
Yes they were, I think one got at least 65 years in prison! I could be wrong about the length of time, but they did get convicted!