A 65-year-old man died Friday after being found outside his Des Moines area home in his wheelchair in subzero temperatures.

Two trash collectors found Leonard Norman Nance in snow about 6:30 a.m., the Polk County sheriff's office said. He was found with a snow shovel in his hand.

The temperature at the time was 15-below zero, said Lt. Joe Simon of the sheriff's office.

Nance died shortly before 10 a.m., said Amy Varcoe, a spokeswoman for Iowa Methodist Medical Center in Des Moines.

An autopsy was planned to determine the cause of death, she said.

"It appears that (Nance) was attempting to shovel his driveway when he succumbed to the frigid temperatures," Simon said.

According to the National Weather Service, overnight temperatures in Des Moines dropped to 18 below zero.

Simon said he didn't know how long Nance may have been outside his home in a rural area of the county. He said he didn't know if Nance lived alone, but no one else was at home when he was found.

Simon said he didn't know how Nance was dressed when he was found.

"It appears he was out shoveling his driveway because when the witnesses found him he had a shovel in his hand," Simon said.

Simon said two workers with Artistic Waste Services Inc. discovered Nance unresponsive in his wheelchair in the driveway not far from the house.

Simon said he couldn't be certain whether Nance got stuck in the snow or if a medical condition may have been a factor in his death.

"There was no family there at the time. Other than the physical impairment, we don't know of anything else," Simon said.

Simon said the two workers, George Clark and Kevin Casey, who were on their normal route called 911.

A telephone call to Artistic Waste Services was not immediately returned.

"They could see a light on his wheelchair and that drew their attention to him," Simon said.

He had no other details about the light, but said he thought the wheelchair was motorized.

A telephone call to Artistic Waste Services was not immediately returned.

Simon said sheriff dispatchers told the two workers to take Nance inside and put blankets on him. Deputies and fire officials arrived and took Nance to the hospital.