The rare occurrence was captured by the zoo’s Panda Cam on Saturday.

When breeding giant pandas in captivity it’s difficult to have just one born, but the Smithsonian’s Mei Xiang surprised everyone by giving birth to two seemingly healthy cubs.

The whole birth was captured on video by the zoo and got so many immediate views that the video crashed.

The first cub has already been examined by vets at the Smithsonian. It was vocalising well and appeared to be strong.

The World Wildlife Fund (WWF) report less than 2000 giant pandas left in the wild, so breeding them in captivity is vital to their survival.

The birth of the twins is a major score for conservationists around the world.