The incident occurred when Perevalova was cleaning one of the enclosures. She reportedly violated the established safety procedures. “An investigation is ongoing, but it can already be said with certainty that it was a fatal mistake,

A group of lions mauled a zookeeper to death at one of Europe's largest big-cat parks on Wednesday after a door inside their enclosure was left unlocked, investigators said.

The employee died after she "went to clean a cage with three lions, without shutting the bolt of a door between two rooms of the enclosure," investigators said.

She apparently didn't lock the internal door in the enclosure that separates her from the three lions and they attacked her, the committee said in an official statement. The park's owner identified the victim as Leokadia Perevalova and called the incident a tragic mistake.

A worker at a wildlife park in Crimea died Wednesday when she was attacked by lions, officials said. According to the Russian Investigative Committee’s office in the