There is sad news from the National Zoo in Washington — the giant panda cub born last week has died.

Zookeepers say they heard the baby's mother, Mei Xiang, giving a distress call Sunday morning. Veterinarians tried to restart the cub's heart and tried other lifesaving methods, but to no avail.

The zoo calls the baby's death heartbreaking. The cub appeared to be in good health all week and showed no signs of injury or infection.

Mei Xiang gave birth last week after five previous false pregnancies since 2007.

Pandas born in captivity are rare. The National Zoo has had just one cub survive more than a few days since 1972. Others have been born and survived in zoos in Atlanta and San Diego, and in China.