The gunman first drove up to a vehicle stopped at a traffic light, according to a police news release. He spoke with the driver, a 23-year-old man from Bridgeport, Conn., before shooting him several times.
The gunman continued driving and shot to death a 22-year-old Irvington man walking on a sidewalk, police said.
The gunman then passed an Irvington police patrol car, backed up and told the sergeant inside, a 24-year police veteran, that a shooting had just taken place, police said. He then drew his gun and shot the sergeant.
The Connecticut man drove himself to a hospital in Newark, and an ambulance took the sergeant to a hospital. The sergeant was treated and released.
In at least two cases, there were reports of a gunman fleeing in a light-colored sport utility vehicle, Loriquet said.
Sunday's shootings followed a night of mayhem on Friday. Five people were shot and three others stabbed in four separate incidents in Irvington.