Inbound Train No. 708 hit a person between the Hazel Crest and Calumet stations around 8:15 a.m.
Inbound and outbound service was temporarily stopped for an investigation.
Officials said a female was sitting on the platform with her legs dangling and sustained injuries to one foot. She is expected to be OK.
Metra advised riders to listen for real-time announcements on trains and on platforms or check the Metra Electric Twitter account or metrarail.com for the latest updates.