An American coroner died of overheating while he was delivering a courier on a very hot day

Peggy Frank, 63, was found dead in her truck in July after delivering mail in the sweltering heat, her family said.

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A US postal worker found dead in his truck in July died of overheating, while temperatures in California reached 117 degrees, the coroner's office said on Monday.

Peggy Frank, 63, died of hyperthermia, or an abnormally high body temperature, reported the Orange County Register. Frank, who was insensitive to his truck in Woodland Hills, had pre-existing health problems, including obesity and heart disease.

A post-American worker died in California after shipping a letter in extreme heat.

Frank, a grandmother, had worked for the United States Postal Service for 28 years. The day Frank died, temperatures reached 117 degrees in the region.

Robert Tipton, one of Frank's neighbors, told FOX11 in July that the overwhelming heat on Frank's death day was like "a wall" hitting him.

"It was almost 120 degrees outside – when I went out, it was just a wall of heat that was hitting you," Tipton said. "It's one of the hottest days of my life in the valley."

"She liked what she did because she loved people … I do not think they realize what kind of work it is … it does not …" is not an easy job, "said Frank's sister, Lynn. "She was a type of person where she wanted to do it and she wanted to do a good job."

Associated Press contributed to this report.