First, call for help. Notify the police if someone’s injured, call 911 and ask for an ambulance or for medical care or a first responder. Then you should cooperate with the investigation by the police. After that’s happened you need to take some time to assess the situation and determine whether or not you need to see a lawyer.
Not everyone who’s in an accident or a car wreck require a lawyer. But if you have suffered an injury that require medical care then you almost certainly need to call an injury lawyer and at least consult with to evaluate what to do next.