A black St. Louis police officer, who was off duty when he heard a commotion near his home and tried to help fellow officers arrest three black suspects, was shot by a white officer who did not recognize him, police said.

A white officer who had just arrived on the scene of a suspected crime Wednesday night saw the off-duty black officer walking toward other officers and shot the officer in the arm "fearing for his safety," a police statement said.

The wounded officer, who is 38 years old and has been with the department 11 years, was taken to a hospital and later released.

The incident began with a report of a stolen vehicle. Police followed the vehicle and the suspects inside opened fire at officers' vehicles until they crashed the vehicle believed to be stolen. The suspects got out of their vehicle and ran.

The off-duty officer heard the commotion from his home nearby and rushed to the scene with his department-issued weapon. Two officers ordered the off-duty officer to the ground, but then recognized him and told him to stand up and walk toward them. As he was doing so, another officer arrived and shot the off-duty officer "apparently not recognizing" him, police said.

The officer who shot the off-duty officer is 36 years old and has been with the department more than eight years.

Officers shot one of the suspects in the ankle. He was taken to a hospital and treated for his wound. He's now in custody.

A second suspect was arrested at the scene. A third remains at large.

Police said they are continuing to investigate.