Lesson learned.Call 911 no matter what and get license plate fir

A long time American friend told me I shouldn't have pitied on the young Mexican driver.  She said I should call 911 and say there was injury. Otherwise police won't come. After they come, I can sign a release form not going to the hospital. And make sure get the license plate first to prevent the at fault car run away. She was right. I asked the young guy to take photos of all three cars and sent them to me--my phone's memory was full and only took one photo. I just found out he only took photos of the damages to my car, his car and the third driver's car but not the front of his car--that would be direct proof how bad he hit my car but he didn't take it.  You can't be too nice in accidents. I'm just grateful to the fourth car driver, a woman, who came forward to leave us her contact information as a witness. I had no idea there was a third car involved. She was a good Samaritan. My colleagues were saying they wouldn't volunteer to be stranger's witness. She's really kind and it must be God's blessing.