ON 4/18/13 AT 2125 HOURS, UNIT 1 WAS TRAVELING EASTBOUND IN LANE TWO OF NORTHERN AVENUE APPROACHING NORTH 59TH AVENUE. UNIT 2 WAS IN LANE TWO OF EASTBOUND WEST NORTHERN AVENUE STOPPED FOR A RED LIGHT AT THE INTERSECTION WITH NORTH 59TH AVENUE. UNIT 2, A BUS, WAS PARKED IN BUS PULL OUT JUST EAST OF NORTH 59TH AVENUE ON WEST NORTHERN AVENUE WITH THE DRIVER OF THE BUS NOT IN DRIVER SEAT BUT STANDING IN BUS. ACCORDING TO DRIVER OF UNIT 1, WHILE UNIT 1 WAS SLOWING TO STOP BEHIND UNIT 2 THE ENGINE OF UNIT 1 BEGAN RACING AND DID NOT STOP EVEN AS THE DRIVER OF UNIT 1 PRESSED THE BRAKES. UNIT 1 STRUCK UNIT 2 IN THE REAR AT LEAST TWICE PUSHING UNIT 2 INTO INTERSECTION. UNIT 2 DRIVER STATED AFTER BEING HIT AT LEAST TWICE BY UNIT 1, UNIT 2 CROSSED INTERSECTION AND STOPPED IN FRONT OF THE BUS TO GET OUT OF THE WAY OF UNIT 1. UNIT 1 ALSO CROSSED THE INTERSECTION OF NORTH 59TH AVENUE AND UNIT 1 STRUCK REAR END OF UNIT 3. DRIVER SIDE PASSENGER OF UNIT 1 WAS TREATED BY GLENDALE FIRE LT157/B-SHIFT AND TRANSPORTED TO HOSPITAL BY SOUTHWEST AMBULANCE B-SHIFT ON INCIDENT NO. 13-121969 AND FOUND TO HAVE FRACTURED LEFT HUMERAL (ELBOW) BY DOCTOR F CONJURSI, MEDICAL RECORD 1173763. DRIVER OF UNIT 1 WAS ISSUED CITATION NO. 862591 FOR ARS 28-701.A AND ARS 28-3151.A.