Troopers from the Wayland post of the Michigan State Police reported Thursday night that a woman was struck and killed by a vehicle on the U.S.-131 expressway just north of the Wayland exit.

Authorities said it wasn’t clear yet what caused the incident near the 66 Mile Marker and 138th Avenue in Leighton Township.

Troopers said the woman, 72, of Grand Rapids, had pulled her vehicle over onto the shoulder of the highway because of an issue with a tire. She had exited her car and was in a traffic lane when she was struck and killed, police indicated. The driver of the other vehicle was said to be a 44-year-old Kalamazoo man.

Neither of the people involved in the incident have yet been identified. It’s unknown if drugs or alcohol were factors, but the Kalamazoo man was wearing a seat belt.

The expressway was shut down between the Wayland (No. 64) and Dorr (No. 68) exits and motorists were advised to seek alternative routes.