CHICAGO (AP) — Chicago police say one of the two plain-clothes officers who were shot and wounded as they sat in an unmarked vehicle has been released from the hospital.

Chicago Police Department spokesman Anthony Guglielmi (goo-lee-EHL’-mee) said Wednesday that the other injured officer remains hospitalized. He says police are investigating, including questioning several people and expediting the processing of ballistic evidence and gun traces.

Guglielmi has said that police believe the officers were “definitely targeted.” Officials said the injuries weren’t life threatening.

The two officers were shot late Tuesday on the city’s South Side. Authorities say they were in an unmarked vehicle when two other vehicles pulled up alongside the officers and opened fire. Police say the officers were conducting a follow-up investigation to a previous incident when they were shot.