A female tiger at a Colorado zoo has passed away after a mating session turned aggressive on Wednesday.

According to 9NEWS, Zoya passed away a few hours following the accident in an indoor den at the Cheyenne Mountain Zoo in Colorado Springs with another tiger named Ivan, who she was paired with through the Species Survival Plan.

Both Zoya and Ivan had successfully bred several times earlier this week, and interactions have been positive between them over the last few months, say zookeepers. But in the mating session on Wednesday, Zoya became aggressive and sustained a life-threatening neck injury when Ivan defended himself against her.

Ivan wasn't significantly injured during the incident.

Zoya was born at Cheyenne Mountain Zoo on June 19, 2008, where she was raised by zoo staff. After several years of failed breeding with another tiger, the proud father of 3, Ivan, moved to the zoo in December in a new attempt to breed Zoya.

Even though Zoya has passed away, her bloodline may continue. The zoo harvested eggs to be fertilized by previously collected semen from the other tiger, Grom. Until another female tiger can be implanted, the eggs will be cryogenically frozen.