(CNN) A lioness at a German zoo has killed and eaten her two newborn cubs just days after giving birth, to the horror of her keepers.

Kigali, a first time mother, gave birth to two cubs at Leipzig Zoo in Germany on Friday, the first lions to be born there in 15 years. Maria Saegebarth, a spokesperson for the zoo, told CNN that the lioness initially took good care of the cubs.

On Monday evening, however, while grooming the newborns, Kigali killed and ate them. She displayed no unusual behavior before eating her cubs, Saegebarth said, and had been eating normally throughout the day.

The zoo announced the deaths in a post on its Facebook page, saying staff were "shocked and sad" at the turn of events. Kigali would soon be returned from the maternal area to the main enclosure, where she would be reunited with Majo, the cubs' father, it added.

Leipzig Zoo in Germany, where lioness Kigali killed her newborn cubs.

Because Kigali ate the cubs in their entirety, an autopsy cannot be performed on them to determine whether they were ill, which may have triggered their mother's actions, Leipzig Zoo said. "This is a kind of natural behavior as it happens in nature, too," Saegebarth told CNN.

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