At that point, she said, the whale "took off really fast, and then he came back around to the glass, jumped up, grabbed the trainer by the waist and started shaking her violently. The last thing we saw was her shoe floating."
Audience member Eldon Skaggs told AP news agency the whale had "pulled her under and started swimming around with her".
A male spectator who witnessed the tragedy gave CNN a similar version of events.
Brazilian tourist Joao Lucio DeCosta Sobrinho and his girlfriend were at an underwater viewing area when they saw the whale with the trainer in its mouth.
The entertainment park, known for its killer whale, seal and dolphin displays, was closed after the incident. SeaWorld in San Diego also suspended its killer whale show.
Tilikum is said to have been involved in previous incidents, the BBC's Andy Gallacher reports from Florida.
A SeaWorld spokesman said the orca had been one of three whales blamed for killing a trainer in 1991 after she had fallen in a pool at a marine park in British Columbia, Canada.
After the whale - nicknamed Telly - was sold to SeaWorld Orlando it was involved in a second incident when authorities discovered the body of a naked man lying across his back in 1999.
Officials later concluded the man, who had either crept into SeaWorld after closing time or hidden in the park until it closed, probably drowned after suffering hypothermia.
BBC's Andy Gallacher: Reports say this whale has a dubious past
There have been incidents involving other whales at SeaWorld.
In November 2006, a male trainer escaped with a broken foot after he was bitten and held underwater by a female killer whale during a show at SeaWorld's San Diego park.
In 2004, another whale at the company's San Antonio park attempted to bite a trainer, but he too escaped.
Though called a killer whale, the orca (Orcinus orca), is actually the largest member of the oceanic dolphin family.
Animal rights group Peta says it has long been asking SeaWorld to stop taking wild, ocean-going mammals and confining them to an area that, to them, is "the size of a bathtub".
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