TORONTO - A rare Sumatran tiger died at the Toronto Zoo on Thursday after she was badly injured in a fight with a younger male tiger, zoo officials said.

The 13-year-old female named Brytne died of a crushed larynx, according to veterinarians at the zoo.

The male tiger involved in the incident was a three-year-old named Harimau Kayu. He had been brought to the zoo from San Diego as part of a breeding program.

Keepers who saw the conflict between the tigers Thursday morning intervened immediately with "emergency measures" and separated the animals, the zoo said.

But staff were unable to save Brytne, described as a "beautiful and loved animal of the zoo community."

Sumatran tigers are listed as critically endangered by the International Union for Conservation of Nature.

It's estimated that about 300 to 500 exist in the wild, while 71 are captive in North America.

Harimau Kayu arrived at the Toronto Zoo in June from the San Diego Wild Animal Park on a breeding recommendation, as part of a species survival program.

Brytne had already produced two litters with another male, Rengat, the zoo said.

Staff had been working over the past six months to carefully introduce Brytne and Harimau Kayu, and get them to reside in the same habitat.

The pair had been showing positive behaviours such as nuzzling and chuffing since October, the zoo said in a statement.

"On rare occasions, in both the wild and captivity, tigers will fight and react instinctively," it said.

Staff at the zoo were said to be "devastated by the loss."

It's another blow for the zoo, which earlier this week announced it was making plans to move its three elephants to a sanctuary in northern California.

Toronto city council voted in October to send the female African elephants to the U.S. facility, where it's warmer and they will have more open space.

The vote followed a campaign by animal rights activists, including former game show host Bob Barker, who argued Canada is too cold for elephants. Four elephants died at the zoo over the past several years.

In October, two newborn polar bear cubs at the zoo died of injuries inflicted by their mother.