Police said the shooting happened near West Roosevelt Road and South Avers Avenue in the Lawndale neighborhood around 2:20 a.m.
A 49-year-old man heard gunshots and felt paint before realizing he had been shot in the back, police said.
A witness told police that a male suspect fired shots at the man from across the street and fled the scene in a white sedan.
The Chicago Fire Department treated the victim and transported him to Mt. Sinai Hospital in serious condition.
Area Four detectives are investigating.
Authorities did not immediately provide further information about the shooting.
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