The Indiana State Police are investigating a crash between a minivan and a motorcycle that left a Plymouth man with potentially life-threatening injuries.

The collision occurred around 3 p.m. on Monday, Aug. 19, at the intersection of Miami Trail and State Road 106.

The preliminary investigation indicates that a Honda minivan, driven by a 36-year-old South Bend woman, was traveling southbound and is believed to have disregarded the stop sign at the intersection.

The woman allegedly drove into the path of an Indian motorcycle operated by the 61-year-old Plymouth man, who was traveling westbound.

The minivan collided with the side of the motorcycle, and the man was thrown from his bike.

The woman was taken to Memorial Hospital with non-life-threatening injuries.

The motorcycle operator was airlifted to Memorial Hospital with serious injuries.

Police say he wasn’t wearing a helmet.