Authorities on Monday released the identifications of a young man and two young women who died after attending the Hard Summer Music Festival this past weekend at the Auto Club Speedway in Fontana.
Derek Lee, 22, of San Francisco, and Alyssa Dominguez, 21, of San Diego, died early Sunday, according to the San Bernardino County coroner's office. The second woman, Roxanne Ngo, 22, of Chino Hills, was pronounced dead Monday around 3 a.m.
Their deaths were not believed to be related, and each was being investigated separately, according to the San Bernardino County Sheriff's Department.
Their names were released about an hour after San Bernardino County Sheriff's Department spokeswoman Jodi Miller confirmed to KTLA that three people had died at the popular rave over the weekend.
It was not yet known what led to the deaths, but extreme heat has not been ruled out as a possible cause, Miller told the San Bernardino Sun. Temperatures reached into the 90s on both days, according to the National Weather Service.
Beverly Hills-based Live Nation Entertainment, the event's promoter, issued a statement.
"We were deeply saddened to learn about the deaths of three people who
attended the festival this weekend," Alexandra Greenberg, a spokeswoman for Hard Summer, said in the statement. "While the causes of the deaths have not yet been determined, we ask everyone to keep them in their prayers. Our sincerest thoughts and condolences are with their family and
The three deaths came after two college students, 19-year-old Katie Dix and 18-year-old Tracy Nguyen, died on the first day of the rave in August 2015. The Los Angeles County coroner's officer ruled that both teens died from drug overdoses.
Dix, who had attended Cal State Channel Islands, died of multiple drug intoxication, while Nguyen, a UCLA student, overdosed on Ecstasy, the coroner's office told the L.A. Times.
In 2014, a 19-year-old Emily Tran, of Anaheim, died after attending the same event at the Whittier Narrows Recreation Area.
Dix's parents recently filed a lawsuit against Live Nation and the Los Angeles County Fair Association, accusing the event organizer and venue operator of negligence in their daughter's death.
The venue was moved from the Fairplex in Pomona to Fontana after the deaths of the two young women sparked changes to future raves held at L.A. County locations, as well as the cancelation of one that was scheduled for September 2015.
Some 325 arrests were made at this year's festival, mostly related to narcotic, sheriff's officials told KTLA.
One of the arrestees had tried to bring various drugs -- including marijuana and methamphetamine -- into the venue, but was intercepted by deputies, authorities told the Sun.
About 147,000 people attended the two-day music festival.
There have been at least 24 confirmed drug-related deaths across the country since 2006 among people who went to raves organized by Los Angeles-area companies, the Los Angeles Times reported. Twelve people died in Southern California — four in San Bernardino County and eight in Los Angeles County — and five in the Las Vegas area, the newspaper reported.
KTLA's Jennifer Thang and Melissa Pamer contributed to this story.