After a horse died on the set of Amazon’s The Lord of the Rings: The Rings of Power, an animal rights group called Peta spoke out against the use of real animals in movies.

The horse died because its heart stopped beating, according to the Guardian.

A spokesperson for Amazon Studios said Sunday morning, “We are very sad to confirm that a production horse has died.”

“The accident happened in the morning when the horse was being worked out before rehearsals.”

“The trainer wasn’t dressed up, and filming hadn’t started yet. At the time, a vet and a person from the American Humane Association were there. The horse died of heart failure, which was confirmed by the independent autopsy.”

Sources told Deadline that the horse was standing close to 20 other horses when its heart stopped beating. It was said that there were 30 other horses on set that day.

In a statement, Peta also asked that CGI be used instead of real animals in movies and TV shows.

Lisa Lange, the senior vice president of Peta, said, “It seems like living underground with orcs is normal for the producers of The Rings of Power, since they can use CGI, mechanical rigs, and other humane methods.”

“Peta wants the creators of the show and all other producers to start a new quest without using real horses.”

The Devil’s Horsemen provided the horses used in season 2 of The Rings of Power. The company has been in business for thirty years and has previously worked with Game of Thrones, The Crown, and Hollywood movies.