BAY CITY, Mich. (AP) — At least three Michigan deer hunters have died of heart attacks during the current 16-day season, including two men who tried to drag the heavy animals away, authorities said.

“I have never seen three people die of a heart attack in 48 hours while deer hunting,” said Dr. William Morrone, the medical examiner for Bay, Midland, Tuscola, Arenac and Iosco counties.

He said hunters need to better prepare for the rigors of the outdoors.

“Deer season comes along and bam: I’ve got a rifle, I’ve got a backpack and I’m trudging through the woods,” Morrone said.

The hunters – men aged 57, 65 and 83 – died in the provinces of Arenac and Tuscola. They make up just a fraction of the thousands of people participating in the traditional firearms deer season, which began Nov. 15.

Morrone suggested the Department of Natural Resources should require physical proof for hunters.

“Better diets, more activity and everyone should think about physical training for this,” he said. “Because deer hunting is a big deal in this state, but it also puts a strain on the body.”