Temperatures reached into the upper 90s during the weekend event in Fontana, California.
Three people died over the weekend after attending the Hard Summer Music Festival in Fontana, California.
A man and a woman died at hospitals in the early hours of Sunday after attending Saturday's festival, San Bernardino County officials said. They were identified as 22-year-old Derek Lee of San Francisco and 21-year-old Alyssa Dominguez of San Diego.
A 22-year-old Chino Hills woman, Roxanne Ngo, also died at a hospital early Monday after attending Sunday's festival.
Their deaths were not related, officials said, and their causes of death were under investigation. More information was not immediately available.