PHILADELPHIA (AP) — A traffic stop in a Philadelphia neighborhood ended in gunfire when authorities say the driver backed into the officer’s cruiser and Arvin Robertsthen pinned him against a wall, spurring the officer to fire several shots into the vehicle.

The driver sped off but was soon found wounded in the vehicle and died a short time later.

The officer, who was on patrol by himself, tried to stop the car around 7 p.m. Thursday. Three witnesses reported the vehicle backed into the officer’s cruiser and, as the officer approached the vehicle, it moved and pinned him against a wall, city Police Commissioner Kevin Bethel said.

The officer then fired several shots into the vehicle, and a passenger in the car got out and was detained there by the three witnesses as the driver sped away, police said. The vehicle was soon found in an alley not far from the traffic stop site, and the driver was inside and had gunshot wounds to the head and body, police said. He was taken to a hospital but was pronounced dead a short time later, police said.

The names of the driver and the officer have not been released. The officer, who has served on the force for about eight years, suffered injuries to both legs and remained hospitalized Friday. No other injuries were reported.

The shooting remains under investigation.