You've called 911, and you're waiting for police and emergency crews to arrive. Even if no one is hurt, police should be called to document the accident.
Exchange information with everyone who's at the scene. If it's a car accident, talk to the other driver involved and get the following information: name, address, and phone number; the make, model, and year of the car; driver's insurance information; car registration; and driver's license number. Also talk to witnesses, including any passengers, and document their names, addresses, and phone numbers.
Pay attention to, and record, the details. Note the time, weather conditions, road conditions, landmarks, and anything else you feel may be important.
Snap photos of the accident scene, including damage, the property, roads, landmarks, and anything else that could be important.
Don't apologize or cast any blame. It may be difficult to do when you or someone else is hurt, but words can be twisted. Even a simple "I'm sorry," or, "What were you thinking?" may be used against you.