The first train on the CSX rail line hit the individual just after 3:35 a.m. at 90 E. Jefferson St., officials said.
Then another freight train came through the area and couldn't stop in time.
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Fire officials responded to a train overpass on Eastern Avenue near 90 E. Jefferson St. about 3:40 a.m., Joliet Fire Chief Jeff Carey said.
The person was pronounced dead at the scene. His name and age haven't been released.
Rock Island main line service was temporarily suspended at Joliet; minimal Rock Island service will operate from New Lenox, Metra tweeted just before 5 a.m.
Heritage Corridor main line train service was also temporarily suspended, the commuter rail tweeted about the same time.
Heritage Corridor service was expected to resume after 7:20 a.m. with delays, Metra said.
Metra police are handling the death investigation.
This is a developing story; check back with ABC7 Chicago for updates.
Sun-Times Media contributed to this report.