The Smithsonian National Zoo in Washington says its rare giant panda called Mei Xiang has given birth to twin cubs.
The first cub was born on Saturday (local time) at 5:35pm and the zoo said on Twitter that a second was born at 10:07pm.
The zoo has said both cubs appear healthy.
If the cubs survive, they would be the 17-year-old panda's third and fourth surviving offspring.
Mei Xiang's first cub, Tai Shan, was born in 2005 and returned to China in 2010.
Her second cub, Bao Bao, turns two-years-old on Sunday and still lives at the zoo.