Indiana State Police said the two-vehicle crash happened on I-65 near the U.S. 231 exit in Crown Point.
Indiana State Police said a minivan occupied by seven adults was "traveling in the right lane at an extremely low speed, approximately 10 to 15 mph, while following another vehicle experiencing mechanical issues."
The driver of a Chevrolet struck the rear left side of the minivan after not realizing how slow it was traveling, police said. The minivan crashed into a ditch.
"Further investigation revealed that only the two front seats remained installed in the minivan," Indiana State Police said. "The remaining five passengers were seated on boxes of mangos and were not properly restrained."
Four people were taken to hospitals with severe injuries, where one person later died, police said.
The Lake County Coroner's Office said 25-year-old Navya Gadusu of Chicago suffered blunt-force in the crash and was pronounced dead at Franciscan Health Crown Point.
The interstate was shut down for several hours, but it has since reopened.
Authorities continue to investigate.