As a trained first responder, the first thing to do is make sure all parties are not injured. If there are injured, call 911, or if a trained first responder is busy tending to injured, and others are around one person is ordered to call 911. After EMT's arrive, then you can proceed with all the rest that was described in this. Also, as our own club member just learned, use your cell phone and videotape all that you can. Photo's don't suffice in this day and age, as our law enforcement never can tell who's telling the truth, no matter how absurd one side's of the story is.