I am sorry for your unfortunate incident but the first thing to remember when in an accident is to take pictures, of the damage, of the other driver, of his license plate, of any witnesses and their license plates if they won't give you their info, and anything else possibly relevant.
Without this information you can easily be shit out of luck, especially if the other driver writes down his info but what he writes is not accurate, and then he drives away. This happened to a friend of mine, the other driver turned out to not have insurance. My friend took a picture of his license plate however so he was busted.