A Thai elephant, who had appeared in several films, crushed his keeper to death with his trunk at a Chiang Mai zoo on Monday morning, according to reports. Somsak Riangngern, 55, was killed by the 32-year-old male elephant, named Phlai Ekasit, as Riangngern's wife, Jampa, watched.

Riangngern, who had tended to the elephant for a decade, was feeding him bananas and walking him to his bathing area when the elephant attacked him. Bystanders alleged that the 10,000-pound elephant struck Riangngern with his trunk several times. The attack lasted more than five minutes, according to local media outlet Khaosod English.

“The elephant suddenly turned back and used his trunk to grab the victim,” said Wuthichai Muangman, acting director of the Chiang Mai Zoo, according to Agence France-Presse. “Then the elephant used his trunk to crush him.”

“This accident was an unpreventable tragedy, since Somsak was an experienced mahout (keeper) who has always loved Phlai Ekasit. We are deeply sorry to his family,” he added.

Phlai Ekasit had appeared in several martial arts films as well as advertisements.

Zoo officials calmed the elephant down later, but remained unsure of the causes of the attack, as the elephant had no previous history of violence. They said a possible factor could have been the heat. Thailand has been well-known for its elephant tourism trade, with a July report by World Animal protection reporting twice as many elephants were involved in Thailand’s tourism industry as the rest of Asia combined. Out of 2,923 elephants recorded working in Asian tourism, 2,198 were found to be in Thailand. Most were kept in “severely inadequate conditions.”

Animal rights group PETA said the keeper’s death was tragic, but that it also showed the possible violent repercussions of keeping animals confined.

“Is it any wonder that some of these gentle animals eventually become fed up and fight back after being chained while confined to small enclosures that are a fraction of the size of their natural habitats?” the statement read.