A white police officer shot and wounded an off-duty black officer who had been trying to help with an arrest in St. Louis last week, a “friendly fire” shooting that again drew national attention to the role race plays in decisions by law enforcement officials to open fire.

The shooting took place around 10 p.m. on June 21 when officers tried to stop a car that had been reported stolen, Lawrence O’Toole, the interim police chief of the St. Louis Metropolitan Police Department, said in a statement. Three people in the car opened fire at the officers, then fled on foot when the vehicle crashed. After an exchange of gunfire with the police, one of the suspects was shot in the ankle.

The off-duty officer, a 38-year-old black man with 11 years of service, was inside his home nearby when he heard the commotion. Taking his police-issued weapon, he went outside to help, the statement said.

When he approached the scene, two of the officers told him to get on the ground but then recognized him and ordered him to walk toward them. But another officer who had just arrived, a 36-year-old white man with more than eight years of service, did not recognize the black officer. That officer, “fearing for his safety,” the police statement said, fired a shot. The black officer was hit in the arm; he was treated in hospital and released, the police statement said. Neither officer’s name has been released.