China says its border soldiers acted in self-defense by shooting at Tibetans attempting to cross into Nepal. Mountain climbers who saw the incident say the soldiers acted more like hunters. The incident has prompted an official complaint by the U.S. government.

Several foreign mountaineers were climbing on the Chinese side of the Nangpa Pass, which leads to the Nepal border, on September 30.

The mountaineers have told human rights activists they saw about 30 people, including children, walking toward Nepal.

Kate Saunders is with the group the International Campaign for Tibet and she spoke with witnesses.

"He said first he heard two shots, which may have been warning shots. And then after that he watched at a distance of around 300 yards Chinese security personnel kneeling down, putting their assault rifles to their shoulders, and taking aim and firing. Apparently they fired round after round," she said.

Saunders say the climbers then watched one of the Tibetans fall down in the snow, try to get up, and then collapse again and lie still. Tibetan rights groups say a young Tibetan nun and a second person were killed in the shooting.

Soldiers then led at least 10 captured Tibetan children through the climbers' camp.

Every year, thousands of Tibetans illegally cross the border into Nepal. Some are children sent abroad for better educational opportunities. Others go for religious studies, or to make the long pilgrimage to see their spiritual leader, the Dalai Lama, who lives in exile in northern India.

China has controlled Tibet since the early 1950s and has restricted political and religious activities in the region. The government has made it difficult for Tibetans to travel overseas.

The Chinese government has a different version of the shooting. In a statement released through the official Xinhua News Agency, the government says the soldiers "were forced to defend themselves" after being attacked by the Tibetans.

It also reported that one person had died in the shooting and two others were injured. Xinhua said a second person later died from altitude sickness.

Accounts of the incident drew a protest from the U.S. government. On Thursday, U.S. Ambassador Clark Randt went to the Chinese Foreign Ministry to protest China's treatment of the refugees.

Saunders says there have been other reports of Tibetans being shot at by border guards. However, this was the first time an incident had been witnessed by so many people.