Here are 10 most important things to do if you have been involved in a car accident in Washington State. You may find more detailed information here RCW 46.52.020

Stop.
Never drive away from a scene of an accident. Even if the accident was very minor, pull over on the side of the road and make a report. Leaving even after a minor accident may result in a hit-and-run criminal charge. If the other party involved in the collision stopped, proceed to step 2. If you were involved in a car accident and the other driver drove off (hit-and-run), stop and record everything you remember about the vehicle and the driver that drove off. Make a note of the color, make, model or license plate of the car (even if you remember only half of the plate number) and any details about the driver. Notify the police about the accident as soon as possible within 24 hours.
Protect the scene.
Turn on your hazard lights. If necessary, use flares to alert other drivers about the accident, especially if the accident occurred in a low visibility area or weather conditions. If the cars stopped after the collision, avoid moving the cars. If it is too dangerous to leave the cars where they collided, and if it is safe to do so, take a picture of the way the cars collided before moving the cars to a safer area.
Call 911.
Dial 911 after an accident, to get a police officer to come to the scene of the accident. If anybody requires immediate medical attention, make sure you also request an ambulance.
Take pictures and videos.
If it is safe to do so, get out of your car and take pictures of the damaged vehicles. If you or your passengers have visible body injuries, make sure you take pictures of the injuries. If there are any paint transfers on the vehicles, damage to the vehicles, etc. make sure you take lots of pictures and videos from a variety of angles. Take pictures of the general area and any particular weather conditions at that specific location at the time of the accident. During the rainy season in the greater Seattle area, car accidents increase in frequency and severity, and pictures of the road conditions may be an important piece of evidence.
Exchange Information.
Normally, a police officer should collect contact information of everybody involved. However, just in case the police officer does not come to the scene of the accident, make sure you have the name, phone number, and address of everybody involved in the accident, drivers and passengers. You should ask to see the insurance card for every vehicle involved in the accident. Record the name of their insurance company and the policy number.
Witnesses.
If there are any people around who were not involved in the accident, ask if they saw the car accident. If so ask them for their name and contact information. Witness can be very helpful in determining liability and other disputed facts.
Seek medical attention.
Most car accident injuries are not immediately apparent after the accident. The symptoms usually appear several days after the date of the injury. Even if you do not feel symptoms immediately after the car accident, it is a good idea to schedule an appointment with your doctor. If you have symptoms after the car accident, make sure you go to the emergency room as soon as possible. If you have a serious health condition or pregnant, you should go to the emergency room regardless if you feel symptoms immediately after the accident. If you lost consciousness during or after the accident, you may have suffered a concussion or another type of head injury, and you should seek immediate medical attention. The effects of such head injuries can be permanent without timely and proper medical attention.
Call your insurance company.
Notify your own insurance company about the accident as soon as possible. If you have personal injury protection (PIP) your insurance company will cover your medical bills and reimburse you for your lost wages, until the at-fault party compensates you.
Record everything.
This is a good time to record everything. Some car accident cases take a very long time to resolve, especially if the case is going to be litigated and it is common for parties to forget important details. Consider keeping a daily journal of your symptoms, as well as any other accident related matters in a file. Keep track of your insurance claim, with the name of your claim’s adjuster, names of other parties involved in the accident, your expenses accrued so far for car rental and medical bills, if any.
Contact a personal injury attorney.
Surviving through the car crash and dealing with the aftermath is extremely stressful. You do not have to go through this alone. Consult an attorney to give you a more fact specific advice about your options early on. Many insurance companies will want you to make a statement or accept a low settlement offer fast, and it is best that you consult an attorney before that.
My Injury Law Firm provides free consultations and case evaluations. In addition, we work on contingent fee basis, which means you do not owe the lawyer a fee for the lawyer’s services unless the lawyer recovers compensation for your injuries.