A U.S. woman on a safari outside Johannesburg was attacked and killed by a lion Monday.

Her companion was hurt trying to fight off the animal, but he is expected to survive, according to Scott Simpson, assistant operations manager at Lion Park.

The two were on a self-drive tour when the lion attacked. Their windows were open, Simpson said.

Staff members responded and chased the lion away. Paramedics were also called, but the woman's injuries proved fatal.

Simpson said the lion would be taken to a second property while the park investigates.

The park has had incidents before, all stemming from open windows, he said.

"That's absolutely forbidden at our park," said Simpson. "There are numerous signs, and we hand out slips of paper to all guests warning them to keep their windows closed."

Lion Park, a wildlife center in South Africa's Gauteng province, boasts a variety of animals, including lions, zebras, giraffes and wild dogs.