A longtime United States Postal Service employee was found dead inside her mail truck last week in Southern California, as temperatures reached as high as 117 degrees in the area.

Peggy Frank had worked for the USPS for 28 years and was nearing retirement.

News sources say the 63-year-old was found unresponsive in her mail truck, which, like most USPS vehicles, was not equipped with air conditioning. Authorities are looking into the cause of death.

In a statement, the USPS said it provides mandatory heat-related training to its employees under a national Heat Illness Prevention Program (HIPP). Postal workers are reminded to stay hydrated, wear appropriate hats and clothing, to carry water and ice and to stay in the shade as often as possible.

Today’s highs in Southern California are expected to be in the mid-90s.