Montgomery County Police are investigating a collision that left a 61-year-old man in critical condition after he was struck by a police car that was responding to a call in Gaithersburg.

Just before 11 p.m. Tuesday, a county police officer was responding to a call regarding domestic violence. As the officer was driving on Chestnut Street near East Diamond Avenue, he struck a pedestrian who was in the road, police said. The officer stopped, called on his radio for assistance and started to help the man, according to police.

The pedestrian and the officer, who is a seven-year veteran of the force, were not identified. Police said they will release the identity of the pedestrian once his family is notified and that the officer’s identity will be released later Wednesday.

Police said the pedestrian was transported to an area hospital. The officer was not injured in the crash.

The initial investigation found that the officer was using his car’s lights and siren and that the pedestrian was not in the crosswalk at the time of the incident, according to police.

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