Red light cameras can help communities enforce traffic laws by automatically photographing vehicles whose drivers run red lights. A nationwide study of fatal crashes at traffic signals in 1999 and 2000 estimated that 20 percent of the vehicles involved failed to obey signals. In 2004 alone, more than 900 people were killed, and an estimated 168,000 were injured, in crashes that involved red light running. About half of all deaths in red light running crashes are pedestrians and occupants in other vehicles who are hit by the red light runners.