Help for car incident

I was involved in car accident this morning. I slowed down to stop for pedestrian and felt a small impact from back of my car then stopped my car. I found out that there are several small dents in my back bump and the car behind me was badly hit by a third car. Police came and gathered all the insurance information. I asked for the second driver's insurance but the police told me the case number is what I need , it have all three of drivers' insuarance information and let me leave the scene. The note police gave me just have a case number.It is saying that 'a request for police report will be submitted ten business days after the officer takes the report'.

What should I do for the police report and how should I claim the dense damage in my back pumper. I think it is not my fault in this case.

Please help.

Thanks