Police say a gunman standing on a downtown Chicago subway platform opened fire at an arriving train in a targeted attack.

Police say a male victim was shot at about 7:45 p.m. Thursday. He's in stable condition at a nearby hospital.

Chicago police deputy Supt. Kevin Navarro says the shooter waited for the victim at the Chicago Transit Authority's Jackson station, which is in the city's downtown business district. Navarro says "as the doors opened up, he shot at the specific subject and ran."

The suspect wasn't in police custody as of late Friday morning.

Navarro says it was a startling but rare event. He says there's no general threat to the public. He says detectives are reviewing surveillance footage, and extra subway patrols are planned.