A man with severe autism died after he was left inside a van for over five hours Saturday.

According to officials with Pennsylvania Department of Public Welfare, 20 year-old Brian Nevins died of hyperthermia after he was left in a van for five hours following a trip to the Sesame Place theme park. Nevins was a resident at the Woods Services facility, which provides educational and vocational supports for children and adults with special needs.

According to Bucks County Coroner Dr. Joseph Campbell, the intense heat inside the minivan caused Nevins death. Saturday was the hottest day on record for the year. “This is a horrible tragedy,” Campbell said. “I really feel for his family… He was probably dead within an hour at those temperatures.”

The Middletown Police Department is investigating the incident. There is no word on whether a wrongful death lawsuit will be filed.