CPD said a 49-year-old man was involved in an argument with a woman on a No. 54 bus in the 200-block of South Cicero Avenue in South Austin just after 8 p.m.
The woman pulled out a knife, and stabbed the man in the chest, before fleeing on foot, police said.
Chicago fire crews took the man to Mount Sinai Hospital, where he died, according to CPD.
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His identity has not yet been released.
There is no one in custody, and Area Four detectives are investigating.
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