The killer whale that dragged its trainer to her death eluded SeaWorld staff trying frantically to trap it with nets during the attack, according to witness statements released yesterday.

After minutes of frenzied work to save Dawn Brancheau, 40, the whale was finally corralled, but still refused to unclench its teeth and let go of her body, according to investigative reports released by Florida's Orange County Sheriff's Office.

Investigators said Ms Brancheau died from multiple traumatic injuries and drowning.

"The whale would not let us have her," another trainer, Jodie Ann Tintle, told investigators after the attack.

In the investigative reports, Ms Brancheau's co-workers described the swiftness of the attack and the furious response that came after alarms sounded around the pool.

Employees who were at other pools, behind computers or emptying coolers of fish rushed to the scene.

The reports include the first extensive accounts from employees who witnessed the attacks at the park in Orlando.

Jan Topoleski, who monitors trainers' safety during shows, said he saw Ms Brancheau lying on the deck face-to-face with the 22ft-long, 12,000lb whale and communicating with him just before the attack.

He said the whale, named Tilikum, bit Ms Brancheau's hair and pulled her into the pool within about two seconds. Mr Topoleski sounded an alarm and grabbed safety equipment.

Susanne De Wit, a 33-year-old tourist from the Netherlands, told investigators her group had just walked to a window for a photo when she saw the attack, which occurred in front of about 20 visitors after a noon show.

"Suddenly I saw (the whale) grabbing the trainer ... and pulling her down in the water," she said. "It was scary. He was very wild, with the trainer still in the whale's mouth; the whale's tail was very wild in the water."

Tanner Grogan, who scrambled to help other employees unfurl nets to isolate Tilikum, said the whale at one point let go for several seconds, but snatched Ms Brancheau again by the foot before anyone could react.

The plastic weighted nets - similar to temporary fencing used at building sites - were unrolled and dropped in the water to help direct the whale to a pool with a hydraulic lift.

It was not clear how long it took workers to finally trap the whale in a pool with the lift, which they used to remove it from the water. One witness said it seemed like 10 minutes, but another said it could have been as long as 30 minutes.

But even after the whale was lifted out of the water, Ms Brancheau still could not be freed.

"Tilly was not giving up Dawn," said Robin Ann Morland, another SeaWorld worker.