WASHINGTON - Since birth, zookeepers made a distinction between the smaller giant panda cub and the larger, stronger cub.
The National Zoo said it is hard to keep the tiny creatures thriving, and now, the worse-case scenario became a reality when the tinier twin panda cub died Wednesday afternoon.
"I was very sad to hear about the panda dying and I heard from a colleague at work today," said Kate Tyrrell, a Woodley Park resident.
Tyrrell visits the zoo daily.
"We love seeing the pandas grow, so it's just a sad tragedy," said Tyrrell.
It is a tragedy Tonja Santos had to break to her kids.
"We're lucky these guys are pretty smart and they understand the cycle of life and it just happens," said Santos. "When we found out one of them passed, we were really sad, just a little concerned, we hope the other ones are going to be okay too."
On the heels of the cub's death, the pandas are off exhibit and the panda house is closed at the National Zoo.
Even so, the panda team at the zoo said when dealing with endangers species, every birth is a success.
The cub's death announcement spread just as quickly as its birth and every detail thereafter, including panda mother Mei Xiang's hurdles caring for both cubs.
"She was trying to do her best with both, but was having some challenges manipulating them," said National Zoo chief veterinarian Don Neiffer.
By Wednesday night, nearly 1,300 people had retweeted the National Zoo's tweet saying, "We are sad to report that the smaller of the two panda cubs has died…"
Knieffer stood just steps away from the panda exhibit and described how zookeepers stepped in and started swapping out cubs to provide adequate care for both and what went wrong.
"This morning when our team went into perform the swap again, we immediately noted that the little cub had not increased in weight, appeared weaker and was exhibiting possible respiratory issues," said Knieffer.
On Wednesday night, the zoo's panda team in Washington D.C. and in China will focus on the surviving larger cub, who is described as robust, thriving and with his mother.