Endangered Sumatran Tiger Gives Birth to Two Cubs at Smithsonian's National Zoo (PHOTOS, VIDEO)

A rare Sumatran tiger gave birth to two cubs on Monday in efforts to keep the breed from becoming extinct, according to the Smithsonian's National Zoo.

The tiger named Damai gave birth to the first cub around 6:15 p.m. and the second around 8:23 p.m. Both cubs are healthy, but zoo keepers are monitoring the newborns. Damai is nursing and grooming both cubs, according to the news release.

The National Zoo wants Damai time to bond with the two cubs before exhibiting them in, so the cubs won't be seen by the public until late fall. However, there are cameras set up for viewers to check out the baby cubs.

"Damai came out of her den on Tuesday while keepers were in the Great Cats building, which is a good sign," the National Zoo said in a news release. "That means she is comfortable with the keepers being near her cubbing den. While she was out she appeared very calm and stayed out for quite a while. She ate all of the meat keepers had offered her, and did not seem overly concerned about the cubs."

National Zoo keepers and veterinarians have been closely watching Damai since she began gaining weight.

"Staff trained Damai to participate in ultrasound procedures, which allowed them to confirm her pregnancy on June 21, 2013," the National Zoo said. "Keepers prepared for the arrival of cubs after Damai became restless and began showing signs that she would soon give birth."

Sumatran tigers are critically endangered, with fewer than 500 Sumatran tigers in the wild.

"It's taken more than two years of perseverance getting to know Damai and Kavi and letting them get to know each other so that we could reach this celebratory moment," Craig Saffoe, committee member of the Smithsonian's National Zoo, said in a news release. "All I can do is smile because the team has realized our goal of producing critically endangered tiger cubs. Damai came to us as a young tiger herself, so it's really special to see her become a great mom."

It is Damai's first litter of cubs, fathered by the National Zoo's 12-year-old male tiger, Kavi.The rare Sumatran tiger gave birth to two cubs on Monday in efforts to keep the breed from becoming extinct, according to the National Zoo.