MINNEAPOLIS (WCCO) — A Robbinsdale police officer severed his Achilles tendon Wednesday night during a traffic stop in Crystal, police say.

At 11:03 p.m., the police officer initiated the traffic stop on a vehicle at 48th and Welcome avenues.

The driver immediately got out of the vehicle and was non-compliant with the officer’s commands, police said. The driver then began running when the officer heard what sounded like a gunshot. The noise was also captured on the squad camera recording.

The officer then suffered the leg injury – which was not related to gunfire — and collapsed near his squad. He was treated at North Memorial Medical Center and released.

Later, the Robbinsdale police chief said that the officer severed his Achilles tendon, adding that the noise heard during the traffic stop could have been a loud popping sound of the tendon snapping.

At this point, the chief said, the cause of the noise is unclear.

The officer will need surgery and a lengthy period of time to recover.

One person of interest was detained following the incident, which remains under investigation.