Saola, a long-horned ox, was spotted in a forest in central Vietnam for the first time in 15 years. The animal, which is one of the rarest and most endangered mammals, was captured by an automatic camera trap.

"When our team first looked at the photos, we couldn't believe our eyes," Van Ngoc, WWF-Vietnam's country director, said. "This is a breath-taking discovery and renews hope for the recovery of the species," Chicago Tribune reports.

The camera that photographed the Saola was set by the wildlife group and the Vietnamese government's Forest Protection Department in the central Annamite Mountains.

According to Van Ngoc Thinh of World Wildlife Fund, a Saola has two parallel horns that can grow up to 50 inches (1.27 meters) in length. The animal is so rare that one can identify just by looking at it.

The antelope-like animal was first discovered in the remote areas of high mountains near the border with Laos in 1992 by a joint team from WWF and Vietnam's forest control agency. They found a skull with unusual horns in a hunter's home.

According to Dang Dinh Nguyen, director of the Saola natural reserve in the central province of Quang Nam, before the discovery in September, the ox was last seen in the wild in 1998, The Guardian reports.

In between 1992 and 2013, three Saola's were captured but died after several months, Washington Post reports.

The WWF has recruited forest guards to eliminate snares in the area where the saola was photographed in order to prevent illegal hunting. The snares are largely used to catch deers and civets, which are a delicacy in Vietnam. Poaching is believed to be the greatest threat to the saola's survival.

According to WWF, no more than a few hundred survive in the remote, dense forests along the border with Laos.