A Chicago Police officer was seriously injured Tuesday night after being struck by a hit-and-run driver on the city's West Side.

The on-duty officer, who police refused to identify, was on foot around 6:40 p.m. in the 5100 block of West Congress Parkway when he was struck, Officer Marcel Bright said.

The officer was taken to Stroger Hospital where he was listed in serious condition Wednesday.

Spokesman John Mirabelli said Wednesday that police have  witnesses who saw the accident, but police are not releasing a description of the vehicle. Mirabelli also declined to say what the officer was doing at the time of the accident, saying the matter was "still under investigation."