RUSSELS, Belgium - An animal lover was mauled to death by cheetahs after entering their cage at a zoo in northern Belgium, authorities and zoo officials said Monday.

Karen Aerts, 37, of Antwerp, was found dead in the cage, Olmense Zoo spokesman Jan Libot said. Police said they ruled out any foul play.

Authorities believe Aerts, a regular visitor to the zoo, hid in the park late Sunday until it closed and managed to find the keys to the cheetah cage.

"Karen loved animals. Unfortunately the cheetahs betrayed her trust," Libot said.

One of the cats that killed Aerts was named Bongo, whom the woman had adopted under a special program. She paid for Bongo's food, Libot said.

Animal rights group GAIA called for the immediate closure of the zoo, located 55 miles northeast of Brussels, saying it was unsafe for both visitors and the cats.

Rudy Demotte, the Belgian minister responsible for animal welfare, sent a team to investigate.