A guest at Knott's Berry Farm fell more than 100 feet to her death late Friday night while riding Perilous Plunge, billed by the theme park as having the steepest and highest drop of any water ride in the world.
Knott's officials immediately closed the attraction, and state investigators tried Saturday to determine how the accident occurred.
Lori Mason-Larez, a 40-year-old Duarte resident, "somehow got out of the ride or came out of the ride," said Len Welch of the California Division of Occupational Safety and Health.
She landed in a body of water at the base of the attraction. The Orange County coroner's office said the cause of death was multiple blunt trauma.
Each passenger on Perilous Plunge is restrained by an individual seat belt and lap bar that is checked by operators before the ride begins, said Dana Hammontree, Knott's public relations manager. The belt and bar at Mason-Larez's seat were in their locked positions when the ride completed its run, she said.
Knott's advertises Perilous Plunge, a 90-second ride, as one of its most exciting attractions, rising to 115 feet and hitting a top speed of 50 mph during the descent. Mason-Larez fell as her boat was on its way down, but officials at the Buena Park facility said they did not know exactly where she slipped out of the car.
The ride carries three boats with 24 passengers each, climbing a hill and moving around a corner before hitting a steep flume.
It's the second time in less than a month that a visitor has died on a ride at Knott's. Three weeks earlier, a 20-year-old woman from Congo suffered a ruptured brain aneurysm on the Montezooma's Revenge roller coaster.
Mason-Larez was married and the mother of five children ages 10 to 18, a relative said. Her family declined to comment further.
Knott's was closed to the public Friday for a private party sponsored by Target stores. Mason-Larez was at the park as a guest of her sister, who works at the chain's Duarte store. Steve Michael Lyman, sales floor manager of the store, said employees who were at the amusement park Friday night were allowed to stay home Saturday because of the incident.
The accident occurred at 10:20 p.m. Mason-Larez was immediately treated by the park's emergency medical personnel and paramedics, who arrived from a fire station across the street from Knott's. An ambulance then took her to West Anaheim Medical Center, where she was pronounced dead.
Hammontree said this was the first time anyone had been injured on Perilous Plunge, which opened a year ago.
Employees stationed at the ride Saturday told patrons only that it was closed.
Besides the Knott's tragedies, two other people died this summer on theme park rides in California.
In June, a 28-year-old Fontana woman died after riding the Goliath roller coaster at Six Flags Magic Mountain in Valencia. An autopsy revealed that she suffered from hypertension-related heart disease, and a ruptured brain aneurysm was determined to be the cause of death. A 42-year-old woman died in July after riding a spinning attraction at Six Flags Marine World in Vallejo, apparently from bleeding in the brain.
More than 35 thrill rides are making their debut this year at U.S. theme parks, according to the International Assn. of Amusement Parks and Attractions.
Times staff writer Monte Morin contributed to this report.