PORTAGE, Ind. – A passenger in a semi truck died of “massive head injuries” after falling out of the vehicle on I-94 in northwest Indiana Tuesday night.

The passenger was identified as Steven E. Downing, 20 of Hobart, Ind. according to an Indiana State police release.

It remains unclear if Downing’s actions were accidental or intentional but there is no foul play suspected on the driver’s part.

Police found Downing on the pavement in the outer shoulder of the expressway just west of the Portage exit at 7:19 p.m., according to a release from Indiana State police.

A witness driving in the middle lane behind truck told authorities the passenger door opened. The driver first thought a garbage bag fell out. The witness realized it was actually a person after driving closer, the release said.

No vehicle struck Downing, who was taken to Northlake Methodist Hospital in Gary, Ind. and pronounced dead of massive head injuries, the release said.

Authorities determined the passenger and the driver of the semi truck were in a relationship.