If you’re ever in a car accident, the very first thing you need to do is make sure everyone’s OK. After that, the second most important thing you can do is call the police.
Make sure someone can come out and investigate the cause of the crash and determine what needs to be done afterwards. More harm is done to cases where drivers exchange information and drive away, not realizing they have two very different stories about what happened.
And so it’s always important to have someone who’s experienced in those matters, usually a police officer arrive at the scene, write a report so that everybody knows what happened going forward.