Feb. 24, 2010 -- A female trainer was killed today at SeaWorld's Shamu Stadium in Orlando, Fla., by a 12,000-pound killer whale that had twice before been involved in the deaths of humans, according to police and local media.

Dawn Brancheau, 40, an experienced trainer at the tourist attraction, was pulled into the tank by the killer whale, Chuck Tompkins, head of animal training at all SeaWorld parks, said this evening.

Tompkins told ABC News Orlando affiliate WFTV that Brancheau was rubbing down the whale after an afternoon show, when the incident occurred.

"She was pulled in and she drowned," he said.

Earlier, police had said Brancheau slipped or fell into a tank holding the killer whale, Tillikum, and witnesses described the animal coming to the surface to attack the woman.

"Brancheau was pronounced dead at the park after being recovered from the pool. Orange County Sheriff's Office homicide investigators continue to investigate the death of the trainer who was reported to have 16 years of experience working with killer whales," the Orange County Sheriff's Office said in an e-mailed release.

Tillikum, a male or bull whale, has lived at the park since 1992, and is one of eight killer whales there.

"Currently, deputies with the full cooperation of SeaWorld have secured the scene and homicide detectives have been requested to respond and conduct a death investigation follow-up, along with our forensics unit," said Capt. Angelo Nieves of the Orange County Sheriff's Office in a statement.

One witness, park visitor Victoria Biniak, told WKMG-TV that she watched the whale grab Brancheau.

"He was thrashing her around pretty good. It was violent," Biniak said.

The whale "took off really fast in the tank, and then he came back, shot up in the air, grabbed the trainer by the waist and started thrashing around, and one of her shoes flew off," she said.

Visitors were evacuated and the park closed following the attack.

In a news conference shortly after the attack, police said Brancheau had fallen into the tank.

"We had a female trainer back in the whale holding area. She apparently slipped or fell into the tank and was fatally injured by one of the whales," said Jim Solomons of the Orange County Sheriff's Office.

He added there was no evidence of "foul play."

Dan Brown, vice president and general manager of SeaWorld Orlando, called Brancheau one of the park's "most experienced trainers."

"It is with great sadness that I report that one of our most experienced animal trainers drowned in an incident with one of our killer whales this afternoon," said Brown.

"We have never, in the history of our parks, experienced an incident like this," he said.

"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."

Tillikum's Previous Attacks

Tillikum has been involved twice before in human deaths.

In 1991, trainer Keltie Lee Byrne fell into a tank holding Tillikum and two other whales at Sealand of the Pacific in Victoria, Canada. A homicide inquest found that the whales had prevented Byrne from climbing out of the tank and ruled her death an accident.

After being transferred to SeaWorld in Orlando, Tillikum again was connected to the death of a person in 1999.

The body of Daniel Dukes, 27, was found naked, draped across the giant whale's body in July 1999. Dukes reportedly got past security at SeaWorld, remaining in the park after it had closed. Wearing only his underwear, Dukes either jumped, fell or was pulled into the frigid water of Tillikum's huge tank.

An autopsy ruled that he died of hypothermia in the 50-degree water. Dukes' parents filed a lawsuit against the park later that year, but later withdrew it.

The Associated Press contributed to this report.