First and foremost, call 911 so that emergency responders can provide assistance. In addition, the law requires you to give reasonable assistance to anyone who is injured. However, if you are not trained in the appropriate first aid procedures, do not move someone who is badly hurt; you might make the injury worse. However, you should move someone who is in danger of being hurt worse or killed (for example, in a car fire) even if you do make the injury worse.
In addition, to help prevent additional collisions, try to warn other motorists that an accident has occurred. Placing flares on the road (only if there are no flammable fluids or items nearby), turning on your car’s hazard lights and lifting the engine hood are usually good ways to warn others on the road. Arrange to get help for anyone who is injured, and try not to panic.