PHILADELPHIA—A Philadelphia police officer hospitalized for days after an off-duty motorcycle accident has died.

A department spokeswoman said Thursday that severe injuries proved fatal to Officer Milan Merke.

The 28-year-old officer had been riding his motorcycle in north Philadelphia when he collided with a car on June 8.

Merke was on his way to anti-violence rally when the accident happened. The driver remained at the scene.

It was not immediately clear on Thursday whether charges would be filed.

Merke had served four years on the force.