A killer whale fatally attacked an animal trainer at SeaWorld in Florida on Wednesday, jerking her into the pool and thrashing her around underwater as dozens of horrified tourists watched.
The orca had been involved in two previous deaths, including one at the water park in 1999.
Dawn Brancheau, 40, was finishing a session with Tilikum, a 12,000-pound male killer whale, after a midday show at the Orlando theme park.
Witnesses said the killer whale grabbed her by the upper arm, disappeared underwater with her and swam to the other side of the tank, flailing her around. At least two dozen tourists looked on from above the killer whale tank and from an underwater viewing area.
The incident was eerily similar to one at San Diego SeaWorld four years ago, but that trainer survived.
In Orlando, Brazilian tourist Joao Lucio DeCosta Sobrinho, 28, and girlfriend Talita Oliveira, 20, were at an underwater viewing area when they saw the orca with Brancheau in its mouth.
The couple said they had watched the show two days earlier and returned to take pictures. But this time, they said, the killer whales appeared agitated.
"It was terrible. It's very difficult to see," Sobrinho said.
Brancheau was bleeding from the face or mouth, they said, and the orca turned her over and over as it swam.
A spectator from Michigan told the Associated Press that Brancheau was on a platform massaging the killer whale. The interaction appeared leisurely and informal, Eldon Skaggs said.
Then the orca "pulled her under and started swimming around with her."
Skaggs said an alarm sounded and staff members rushed the audience out of the stadium as workers scrambled around with nets.
SeaWorld President Dan Brown said none of its parks had ever experienced a similar incident. He pledged a thorough review of the park's procedures.
"This is an extraordinarily difficult time for the SeaWorld parks and our team members. Nothing is more important than the safety of our employees, guests and the animals entrusted to our care," Brown said, his voice breaking. "We extend our deepest sympathies to the family and friends of the trainer and will do everything possible to assist them in this difficult time."
Brancheau, who had been employed at the park since 1994, had known she wanted to work there since visiting SeaWorld at age 9, she told the Orlando Sentinel in 2006.
"I remember walking down the aisle and telling my mom, 'This is what I want to do,' " she said.
Brancheau had started working with sea lions and otters, then advanced to killer whales. But she recognized the dangers.
"You can't put yourself in the water unless you trust them and they trust you," she said in 2006.
A SeaWorld official said Wednesday that because of Tilikum's size and his involvement in the two previous deaths, trainers were not supposed to get into the water with him.
SeaWorld said it hadn't decided what to do with him.
But Brancheau's sister, Diane Gross, told the Associated Press that the trainer "would not want anything done to that whale."
Nicknamed Tilly, the orca was one of three blamed for the 1991 drowning of a trainer who lost her balance and fell into the water at Sealand of the Pacific in British Columbia, Canada.
And in 1999, SeaWorld officials discovered the body of a naked man on the killer whale's back. Authorities concluded that the man, who had either sneaked into the park after hours or hidden inside until it closed, most likely drowned after suffering hypothermia in the 55-degree water.
They also said it appeared that Tilikum had bitten the man and torn off his swimming trunks, probably believing he was a toy.
In the San Diego incident, the park's most experienced trainer was dragged to the bottom of a pool during a show by a 7,000-pound killer whale named Kasatka.
The trainer, Kenneth Peters, escaped with puncture wounds and a broken foot after he calmed the orca by stroking it.
The California Division of Occupational Safety and Health investigated the 2006 incident and produced a report predicting that it was "only a matter of time" before an orca killed a trainer at the park. It recommended that SeaWorld be prepared to kill an orca if necessary to rescue a trainer.
SeaWorld officials objected, saying the agency did not have expertise in animal behavior. In March 2007, the agency agreed to withdraw and rewrite the report, focusing only on the incident. The report concluded that SeaWorld had done a good job in training its employees who work with the large mammals and that no major safety violations occurred.
On Wednesday, SeaWorld San Diego canceled its afternoon killer whale show, park spokesman David Koontz said.
"We're terribly saddened by the loss of the member of our SeaWorld family," Koontz said.
Officials at PETA, long critical of SeaWorld's practices, issued a statement calling on the park "to stop confining oceangoing mammals to an area that to them is like the size of a bathtub. It's not surprising when these huge, smart animals lash out."
Orlando Sentinel staff writers Bianca Prieto and Amy L. Edwards contributed to this report.