Panda lovers, rejoice. Mei Xiang, a giant panda at the National Zoo in Washington, gave birth to healthy twin cubs on Saturday, just three days after the zoo’s staff discovered that she was pregnant.

The first birth, at 5:34 p.m., was broadcast live online on the zoo’s Panda Cam and announced on its official Twitter account. The second birth, at 10:07 p.m., was unexpected and was announced on Twitter. The announcement included a picture that appeared to show the cub being examined by veterinarians.

“It appears healthy,” the zoo said on Twitter.

Mei Xiang is a minor celebrity in Washington, and her breeding is watched closely by panda fans around the world. Giant pandas mate infrequently, and the birth of a healthy cub is uncommon. Mei Xiang has never before given birth to more than one healthy cub at a time. Bao Bao, one of her cubs who was born in 2013, was followed a day later by a stillborn sibling.

Besides Bao Bao, Mei Xiang has had only two cubs who survived: Tai Shan, who was born in 2005, and a cub who died in 2012 shortly after its birth.