Ideally, you won't ever find yourself in a car accident. But car accidents are common enough that it's important to know what to do if you ever find yourself in that situation. Here are a few suggestions:
If you've never been in a car accident before, you don't know how you'll react. If you find yourself in an accident and your instinct is to flee, acknowledge that but then stay put, for legal reasons as well as moral. The Massachusetts law requires that all accidents that result in any injury, and/or cost over $1,000, must be reported.
Exchange information, but that's it
Approach the other driver calmly and kindly. Hopefully, he or she will do the same. Exchange name, address, insurance, license plate, and vehicle registration information but avoid discussing the accident. Only talk about the accident with police officers.
If you don't obtain their contact information, you might as well not have a witness in the first place. Make sure you accurately record their contact info, as well as their official identification to ensure accuracy.
Make a picture of both vehicles at the scene of the accident, as well as the other vehicle's license plate. Take close ups of any damages. Also take a mental picture of the driver. In case the other party flees, this will help police track him or her down.
Get medical attention
Do this even if you think you don't have any injuries. Sometimes, injury symptoms don't appear until days later.
Talk to an attorney
Hopefully, you can work this out by keeping it between you and the other driver. Either way, it's important to consult an attorney so that you know your rights and are prepared to take legal action if necessary.