Your safety comes first! The first thing to do in the event of an accident is to check that all parties are OK.
If someone is injured or in danger, call the emergency services and make sure that they are on their way. Then exchange full contact information (full name as on your ID card, email, phone number, address) with the other parties and possible witnesses involved. Take photographs of possible damage to any vehicles or property. Later, and as soon as you can, file a claim for insurance coverage.