if some people had stopped i would advise that other cars carried on like they did. if everything come to a halt then the road would be blocked. then the traffic jam would have built up and seriously delayed the ambulance rapid responce or main abulance from attending the scene.

im a trained first aider, i would have stopped as my knowledge may help save lives. but also they teach you to ensure the surrounding area is clear for access for emergency services. so i'd have asked someone to ensure the traffic keep moving.