The 37-year-old was biking north in the 6400-block of South Kedzie Avenue in Marquette Park about 6:50 a.m. and tried to turn left, when a semi traveling south hit him, police said.
The truck did not stop and drove away, CPD said.
The man suffered a head injury and was taken to Christ Hospital in critical condition, police said.
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No other injuries were reported.
The Major Accident Investigation Unit is investigating.
This is a developing story; check back with ABC7 Chicago for updates.