Esthi Octovia Wara Hapsari, a 24-year-old vet at a tourism centre on Java island, was tending to two elephants when one became violent.
“Suddenly the elephant became ferocious,” said Pardiyanto, the head of the Gajah Mungkur Dam tourism site where the incidence occurred.
“The elephant threw the mahout (keeper) off its back, then attacked Esthi, who was standing nearby.”
Police are investigating why the 5.5-tonne elephant suddenly became violent, after interacting calmly with the vet and keeper moments before.
The local conservation office said the elephant had a record of turning on its mahouts in the past.
It had just been transferred from a zoo to the tourism centre in recent weeks said Pardiyanto, who like many Indonesians goes by one name.
Sumatran elephants are classified as critically endangered by the International Union for Conservation of Nature, a protection agency.
The World Wildlife Fund estimates there are between 2,400 to 2,800 such elephants left in the wild in Indonesia.
The population has dwindled due to poaching and habitat pressures as rainforests are converted for plantations and residential developments.
Conflict between elephants and humans is also on the rise as people encroach on the animals’ habitats. Elephants are often killed either by villagers, who view them as pests that destroy their crops, or by poachers for their tusks.