The National Zoo said Sunday that its giant panda cub - a joyous surprise when born last Sunday - has died.

The Zoo confirmed the death in a statement late Sunday morning.

"Panda keepers and volunteers heard a distress vocalization from the mother, Mei Xiang, at 9:17 a.m. and notified the veterinarian staff immediately," the statement read, in part. "The panda cam was turned off and the staff were able to safely retrieve the cub for an evaluation at 10:22 a.m. Veterinarians immediately performed CPR and other life-saving measures but the cub did not respond."

Dennis Kelly, the zoo's director who referred to the death as "extremely devastating," elaborated on the scene at a press conference Sunday afternoon.

"[Mei Xiang] got up and moved from where she was holding the cub and made a honk. The keepers and scientists tell me that a honk was an unusual sign to make, and we surmised that it was a distress call."

The zoo statement went on to say that the unnamed cub was in good condition and showed no outward sign of trauma or infection.

"It was just beautiful," said the zoo's chief veterinarian, Suzan Murray. "Beautiful little body, beautiful little face, the markings were beginning to show around the eyes. [The cub] could not have been more beautiful."

Murray expressed the hope that a preliminary necropsy on the cub would be completed by Monday. Kelly said that the zoo's panda exhibit would be closed "until we are confident that Mei Xiang is safe and healthy."

The cub was unexpectedly born at 10:46 p.m. on Sept. 16. It was the second cub born to Mei Xiang.