As the number of accidents is increasing, it seems like on Earth cars have surpassed the human population. And if it has not superseded yet, then certainly car accidents will soon decrease the human population by running over people.
Though there are so many traffic rules and regulations have been implemented, but car accidents do happen. After all, accidents happen accidentally. The same has happened here. When cars were waiting for the signal to turn green, suddenly a police car at high speed smashed the other car.