Striking a pedestrian is a serious matter, and a driver could even face criminal prosecution depending on the facts of the case. Due to the severe nature of a pedestrian accident and the fact that drivers may be apprehensive about involving the police, they might try to bargain with you to resolve the matter between you.
Under no circumstances should you agree to such an arrangement. In some cases, a driver may even attempt to flee the scene. You should always call the police from the scene of a pedestrian accident, no matter how minimal you believe your injuries might be.
It is not too late if you left the scene and did not call the police. The law allows you to file a police report as soon as possible. Call the police or go to the nearest police station for further instructions on completing the process.