From a legal standpoint you should stay at the scene, check on all drivers and passengers, call the police, and exchange insurance information.
Now the medical procedure is stop and park your car in a safe area and call 911, turn on hazard lights, raise hood to cause more attention, make sure everyone is safe, ask driver to turn off ignition, or turn it off yourself, and place flashers or reflectors 250 to 500 feet behind the crash.
Now the medical procedure is stop and park your car in a safe area and call 911, turn on hazard lights, raise hood to cause more attention, make sure everyone is safe, ask driver to turn off ignition, or turn it off yourself, and place flashers or reflectors 250 to 500 feet behind the crash.