Chinese officials say military troops shot in self-defense at a group of about 70 people who the officials say tried to illegally cross the border between China and Nepal last month.

The state-run news agency Xinhua Thursday quotes a regional official as saying the troops encountered the group September 30 in Tibet and tried to persuade the people to return home.

But the official says the group refused and attacked the soldiers.  Xinhua reports that two of the people suffered injuries and that one later died of altitude sickness.

Earlier reports describe a fatal shooting involving Chinese troops in the same area on the same day. It is not clear if it is the same incident. In those accounts, western mountain climbers and other witnesses say they saw Chinese forces shoot and kill a 25-year-old Tibetan nun. 

A Tibetan advocacy group has posted on its web site photos that the group says a climber took at the scene of the shooting.

The International Campaign for Tibet says Chinese soldiers took at least 10 Tibetan children into custody.  

Hundreds of Tibetans cross the Himalayas from their Chinese-ruled territory to Nepal every year. Some try to make the trip to reach a northern town in India, where the exiled spiritual leader of Tibetan Buddhism, the Dalai Lama, lives.