A twelve-year-old lioness has killed her two-year-younger male conspecific in a US zoo. Previously, the two big cats were living together for eight years at the Indianapolis Zoo. In 2015, her three boys were born.

Zuri, the female beast, attacked the lion named Nyack last week before the zoo opened. Employees had become aware of the attack by an extraordinary amount of roar. "Animal keepers tried to separate the lions, but Zuri held Nyack by the neck until he stopped moving," CNN quoted from a message. "Nyack was a magnificent lion and he will be greatly missed," it said.

Indianapolis Zoo / REUTERS

Lioness Zuri

Previously, there should have been no evidence of unusual aggressiveness between the two animals. Now the incident will be investigated. So far, however, there are no plans to change anything about the attitude of the lions.

According to experts, deadly force among zoo animals is very rare, especially in this constellation.