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And then there were two.

Mei Xiang is seen in a screenshot from the National Zoo's live "panda cam" on Saturday, Aug. 22, 2015. (Credit: Smithsonian Institution)
Mei Xiang is seen in a screenshot from the National Zoo’s live “panda cam” on Saturday, Aug. 22, 2015. (Credit: Smithsonian Institution)

Hours after giving birth to a cub, giant panda Mei Xiang delivered a second one Saturday night, the Smithsonian’s National Zoo announced.

“We can confirm a second cub was born at 10:07,” the zoo tweeted. “It appears healthy.”

Mei gave birth to the first cub Saturday evening relatively quickly — an hour after her water broke.

“Mei Xiang reacted to the cub by picking it up. The panda team began preparing for a birth when they saw Mei Xiang’s water break at 4:32 p.m., and she was already having contractions. The sex of the cub won’t be determined until a later date,” the zoo said in a news release.

Zoo officials said the first cub is vocalizing and appears to be in good condition.

“The cub is vulnerable at this tiny size but we know Mei is an excellent mother,” zoo director Dennis Kelly said.

Experts will perform a neonatal exam on the newborn cubs after they retrieve them, which may take a few days.

Mei was artificially inseminated in April using semen from a giant panda in China as well as one living at the zoo, Tian Tian. DNA analysis will determine who is the father.

She has two surviving cubs — Tai Shan, born a decade ago and now living in China — and Bao Bao, who is 2 and lives at the zoo.

When Bao Bao turns 4, she will be sent back to China.