A semi-trailer left the U.S.-131 expressway and rolled over just north of the Dorr exit Tuesday afternoon, killing one person and causing traffic shutdowns between the Dorr and 100^th Street exits.

The crash occurred on the southbound lane on the freeway and both occupants of the semi were ejected.

Cause of the crash isn’t known yet.

Authorities said emergency medical personnel performed life-saving measures, but one of the occupants died at the scene. They added that a second occupant’s injuries were not life-threatening.

Allegan County Sheriff’s deputies said U.S.-131 was beginning to reopen at about 6 p.m., but cleanup was still taking place.