Try to fix the evidence before the traffic police arrive. If you have a camera phone or camera, you should take photos and leave a certificate. If the injured person is in urgent need of rescue and moves, remember to draw the position outline when the vehicle needs to move; Pay attention to whether there were any third-party personnel and vehicles that affected the accident at that time. If there is any impact, the personnel and vehicles will stay at the scene and explain the situation to the traffic police. The accurate time and traffic signals at that time should be recorded; Pay attention to the condition and loading of the other vehicle; For evidence that may change or be lost immediately, you can take photos in time or ask passers-by to testify and sign, and leave the contact information of witnesses; Remember not to let the other party destroy or move the scene. The scene map made by the traffic police shall be confirmed by the signature of the parties concerned, and if there is any objection to the scene map, it shall be put forward in time. The Traffic Law stipulates that the traffic police can detain the vehicle only when it needs to be appraised, and once the inspection is completed, it should be returned to the owner. Therefore, if the injured party thinks it is necessary to detain the other party's vehicle as compensation guarantee, it should apply to the court for property preservation in time and seal up the other party's vehicle.