An 89-year-old man has died after the riding mower he was driving overturned, rolled down an embankment and landed in the Mississippi River, the Sherburne County Sheriff’s Office said.

The body of Ralph A. Hermes was found Monday afternoon by a concerned neighbor, with Hermes’ arm pinned under the mower, the Sheriff’s Office said. It happened at his home off County Road 14 in Big Lake Township.

Investigators believe the riding mower tipped near a 15-foot drop to the riverbank. He was pronounced dead at the scene.