BLACKWELL, Okla. (AP) — The state Medical Examiner's office says a 69-year-old Blackwell man is the latest heat-related death in Oklahoma.

Medical Examiner's spokeswoman Cherokee Ballard says Marcelino Calderon-Mora died Monday of hyperthermia. There have now been four confirmed heat deaths in the state.

Blackwell police Sgt. John Mitchell told The Oklahoman that Calderon-Mora was found unresponsive in a ditch near a Blackwell park about 3:30 p.m. He was taken to Blackwell Regional Hospital, where he died.

Mitchell says Calderon-Mora was known to voluntarily mow lawns.

According to National Weather Service records, the temperature in Ponca City, located near Blackwell, topped out at 103 degrees on Monday.

Ballard says officials are trying to determine if eight other deaths in the state are related to the heat.