MITCHELL, Iowa (AP) — A northern Iowa man has died after getting trapped inside a grain bin.

Mitchell County Sheriff Gregory Beaver said in a Facebook posting that officers responded to a 911 call Wednesday afternoon at a grain bin. First responders arrived to find 69-year-old Dennis Ray Fischer of Mitchell trapped in the bin.

Rescuers tried “for an extended period of time” to free Fischer. He was pronounced dead at the scene. It wasn’t immediately clear how Fischer became trapped.

Beaver urged farmers at harvest time to be aware of the danger of becoming trapped in a grain bin.