On Wednesday the National Zoo announced that the two Giant Panda cubs born there on Saturday had died.

“It was devastating,” said Brandie Smith, the zoo’s associate director for animal care sciences, “The incredible joy that you feel, where you have these two beautiful, fragile, delicate cubs, and you have the awesome responsibility of helping a panda mother care for these cubs — it’s an honor.”

The cub’s twin is doing well so far according to the team of zookeepers taking care of it, according to the Washington Post.

“Every birth is a success. We have a success here,” zoo director Dennis Kelly said.

When the cub was born, it was only 3 ounces while it’s surviving twin was 4.8 ounces. Zoo officials have said that the smaller of the two panda cubs was failing within a few days of being born and was already regurgitating and knot keeping on target weight.

When pandas are born in the wild, if there are twins, usually only one is nurtured while the other one is left to survive, or perish, on its own. In order to prevent this from happening at the National Zoo, the zookeepers had planned ahead to switch the cubs out every four hours with their mother, Mei Xiang, in order to encourage one-on-one time.

Unfortunately, Mei Xiang rejected the plan and for long periods of time would refuse to switch out the cubs, only wanting to keep the larger of the two. But the chief Veterinarian Don Neiffer did report that on Tuesday afternoon, the mother did allow the switch and the smaller cub was with her through the night.

The mother and smaller cub were observed closely during that night and all seemed to be going well. But the next morning, the cub appeared weaker and was having a hard time breathing.

After the zoo’s morning meeting at 10a, the team felt the cub was starting to do better, in very short stages. But not too long after, at 12:30p, Neiffer got a call that the cub’s health was failing. By the time he reached the panda house, over a dozen experts were attempting to keep the cub alive.

At 2p, the cub went into respiratory arrest and then cardiac arrest.

“We had our moments during that two hours where we said, ‘all right, we are going to get over this,’” Neiffer said.

But the team’s efforts were not recognized.

“It was very quick,” he said of the animal’s death. “I don’t know how long the heart was beating after the baby stopped breathing. Probably not very long.”

“I made the call,” he said. “It’s part of the job. It’s not the fun part of the job…. It’s my burden, that I chose.”