A 35-year-old man was on the platform just after 8 p.m. Monday night.
The attacker was arguing with the man and pulled out a knife and cut the other man’s chest and upper left leg.
The victim was taken to Advocate Illinois Masonic Medical Center and treated for a “minor injury,” according to Fire Media information.
Charges are pending against the suspect who is 33-years-old.
Chicago Tribune contributed to this report