During a mating attempt between two Malayan tigers at the San Diego Zoo on Saturday, four-year-old female Tiga Tahun was attacked by her intended mate, Conner, dying soon after of neck injuries and breathing difficulties, The Associated Press reports.

"(The encounter) began with positive interaction between the two big cats. Unfortunately this changed quickly and zookeepers were unable to separate the two animals," the zoo said in a statement, according to the AP. No visitors witnessed Conner attacking and killing Tiga Tahun during the two animals' first intended breeding experience.

Fatal attacks are rare during mating, and previous interactions between Tiga Tahun and Conner led zookeepers to believe that the timing had been right. 

"Everything was spot on," zoo spokeswoman Jenny Mehlow told the AP, explaining that the rare tigers had been rotating between the exhibit and their bedrooms as to familiarize each other with the other's scent before mating was attempted.

Dan Cassidy, general curator of Omaha's Henry Doorly Zoo & Aquarium in Nebraska, which owned the female tiger, confirmed to the AP that behavior during tiger breeding can be unpredictable. Zoos typically have tigers touch noses or paws before they are allowed to interact without barriers.

Tiga Tahun was born in 2009 at the Bronx Zoo after her mother had been transferred from Ohama.

"That cat had never been in Omaha, so it wasn't like we had a personal connection, but everyone is saddened by the loss," Cassidy said.  

Conner was born in 2011 at the San Diego Zoo, one of seven Malayan tigers born at the zoo since 2005, according to the AP.