What is the name of your state (only U.S. law)?
An ambulance turned it's siren on at the last minute before attempting to cross an intersection. The car in front of me panicked and slammed the brakes. I was at least two car lengths before the collision but didn't notice that he had stopped until there wasn't enough time to stop. So I ended up rear-ending him. His truck is fine but my entire front end is totaled. He says that it's his fault but the only insurance that I have is no-fault. So my question is who is at fault and what should I do?