When zoo keeper Sarah McClay was mauled to death by a Sumatran tiger at an animal park in England, its owner alleged she had entered the animal's pen against safety rules.

But police said Monday that's not what happened.

After conducting an investigation, police said the tiger escaped from its pen and attacked 24-year-old McClay on Friday as she was working in a staff area at South Lakes Wild Animal Park in northwestern England.

She later died of her injuries at a hospital.

Cumbria police said they are trying to find out how and why the tiger escaped.

The park owner claimed McClay broke the rules by entering the tiger's pen for an unknown reason.