Not less than fifteen days prior to the holding of any automobile race at a designated public race course designed for that purpose, the sponsor of the race shall apply in writing to the Chief of Police of the territorial district wherein he proposes to hold such race for a permit to hold the race, stating therein the time when and the place where such race is to occur. The Chief of Police shall determine the number of police officers necessary to be assigned to duty at the race for the safeguarding of the public. Nothing in this section shall be construed to preclude the sponsor from employing private security services to supplement the number of police officers assigned to duty.