An American working at a chimpanzee sanctuary in South Africa is reported to be in intensive care after being bitten and dragged along the ground for almost half a mile by two animals.
Reports said the man, a ranger, lost fingers and part of his ear in the attack, at the Jane Goodall Institute Chimpanzee Eden .
Mediclinic Nelspruit, the hospital where he was taken, said he was in a critical condition in intensive care after undergoing surgery on Thursday.
Jeffrey Wicks of the Netcare911 medical emergency services company said the ranger was leading a tour group at the Chimpanzee Eden near Nelspruit, some 180 miles (300 km) from Johannesburg,
The tourists were escorted to safety by members of staff as the chimpanzees dragged the ranger out of their enclosure.
The sanctuary's director fired into the air to scare the chimps off then chased them back into the enclosure, according to press reports.
Mr Wicks says the man suffered "multiple and severe bite wounds" and was dragged nearly a nearly half a mile (1km) by the chimpanzees.
The international institute was founded by primatologist Jane Goodall who opened the sanctuary in 2005.
It is a home to chimpanzees rescued from further north in Africa, where they are hunted for their meat or held captive as pets.
It provides shelter to 33 animals who are kept in large enclosures where they can be seen by tourists who pay £10 to join one of three daily tours.
Dame Jane, 78, is considered one of the world's leading experts on chimpanzees, having travelled to Tanzania in 1960 and spent 45 years studying the mammals.