The San Francisco Zoo, which lost a tiger on Christmas, is celebrating the arrival of a newborn cub.

The cub born Friday belongs to Leanne and George, two Sumatran tigers on loan from a zoo in San Antonio and an aquarium in Denver.

The tiger that was shot by police after killing a teenager and mauling his two friends was a Siberian tiger. Both species are endangered.

For now, zoo staff are keeping their distance from Leanne and her cub and are using a video camera and baby monitors to observe the pair. The zoo's chief veterinarian says the cub was seen nursing and the mother appeared to be "very attentive and gentle."

The cub's birth marks the first time since 1956 that a Sumatran tiger has been born at the San Francisco Zoo.