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CNN) -- A killer whale killed a trainer Wednesday afternoon at SeaWorld's Shamu Stadium in Orlando, Florida, a public information officer for the Orange County Sheriff's Office said.
The 40-year-old woman, identified by sheriff's spokesman Jim Solomons as Dawn Brancheau, was in the whale holding area about 2 p.m. when "she apparently slipped or fell into the tank and was fatally injured by one of the whales," he said.
But a witness told CNN affiliate WKMG-TV that the whale approached the glass side of the 35-foot-deep tank at Shamu Stadium, jumped up and grabbed the trainer by the waist, shaking her so violently that her shoe came off.
WKMG: Killer whale kills trainer
A SeaWorld employee who asked not to be identified confirmed the description of the attack and added that the whale involved is named Tillikum.
SeaWorld uses "Shamu" as a stage name for any of the male or female orcas in its shows.
"One of our most experienced animal trainers drowned" in the accident, said Dan Brown, vice president and general manager of SeaWorld Orlando. He said an investigation will be carried out.
"We'll make our findings known in due course," he said. "We've never in the history of our parks experienced an incident like this. All standard operating procedures will be reviewed." He would not elaborate.
Video: Trainer killed at Sea World
Video: Killer whale kills trainer
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SeaWorld Inc.
"Please bear with us; we've just lost a member of our family," he said.
A patron who did not witness the event said the park refunded her entry fee, although a spokeswoman said the park remained open.
Guest David Dalton told CNN affiliate WFTV, "All of a sudden, out of nowhere, two of the bigger whales just kind of flipped out, going as fast as they could in the water."
A spokesman for People for the Ethical Treatment of Animals called the death "a tragedy that didn't have to happen."
Jaime Zalac said the organization had called on SeaWorld "to stop confining oceangoing mammals to an area that to them is like the size of a bathtub, and we have also been asking the park to stop forcing the animals to perform silly tricks over and over again. It's not surprising when these huge, smart animals lash out."
In 2006, a trainer at the adventure park was hospitalized after a killer whale grabbed him and twice held him underwater during a show at Shamu Stadium.
In 1999, Tillikum was blamed for the death of a 27-year-old man whose body was found floating on his back in a tank at SeaWorld, the apparent victim of a whale's "horseplay," authorities said then.
The Orange County Sheriff's Office said the man apparently hid in the park until after it closed and then climbed into the tank.
The 11,000-pound, 22-foot-long whale was "not accustomed to people being in his tank" and "wouldn't have realized he was dealing with a very fragile human being," Solomons said at the time.
"He may have been a victim of what a whale would call horseplay, just playing around," Solomons said.
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Same killer whale responsible for three deaths already.
The 40-year-old woman, identified by sheriff's spokesman Jim Solomons as Dawn Brancheau, was in the whale holding area about 2 p.m. when "she apparently slipped or fell into the tank and was fatally injured by one of the whales," he said.
But a witness told CNN affiliate WKMG-TV that the whale approached the glass side of the 35-foot-deep tank at Shamu Stadium, jumped up and grabbed the trainer by the waist, shaking her so violently that her shoe came off.
WKMG: Killer whale kills trainer
A SeaWorld employee who asked not to be identified confirmed the description of the attack and added that the whale involved is named Tillikum.
SeaWorld uses "Shamu" as a stage name for any of the male or female orcas in its shows.
"One of our most experienced animal trainers drowned" in the accident, said Dan Brown, vice president and general manager of SeaWorld Orlando. He said an investigation will be carried out.
"We'll make our findings known in due course," he said. "We've never in the history of our parks experienced an incident like this. All standard operating procedures will be reviewed." He would not elaborate.
Video: Trainer killed at Sea World
Video: Killer whale kills trainer
RELATED TOPICS
SeaWorld Inc.
"Please bear with us; we've just lost a member of our family," he said.
A patron who did not witness the event said the park refunded her entry fee, although a spokeswoman said the park remained open.
Guest David Dalton told CNN affiliate WFTV, "All of a sudden, out of nowhere, two of the bigger whales just kind of flipped out, going as fast as they could in the water."
A spokesman for People for the Ethical Treatment of Animals called the death "a tragedy that didn't have to happen."
Jaime Zalac said the organization had called on SeaWorld "to stop confining oceangoing mammals to an area that to them is like the size of a bathtub, and we have also been asking the park to stop forcing the animals to perform silly tricks over and over again. It's not surprising when these huge, smart animals lash out."
In 2006, a trainer at the adventure park was hospitalized after a killer whale grabbed him and twice held him underwater during a show at Shamu Stadium.
In 1999, Tillikum was blamed for the death of a 27-year-old man whose body was found floating on his back in a tank at SeaWorld, the apparent victim of a whale's "horseplay," authorities said then.
The Orange County Sheriff's Office said the man apparently hid in the park until after it closed and then climbed into the tank.
The 11,000-pound, 22-foot-long whale was "not accustomed to people being in his tank" and "wouldn't have realized he was dealing with a very fragile human being," Solomons said at the time.
"He may have been a victim of what a whale would call horseplay, just playing around," Solomons said.
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Same killer whale responsible for three deaths already.
