New Delhi (CNN) -- The Tibetan government-in-exile has called on the international community to take action to halt violence in western China that has reportedly killed several Tibetans and left others wounded.
"The Central Tibetan Administration urges the international community to not remain passive before the current situation," Lobsang Sangay, the head of the government-in-exile, said in a statement Tuesday. "It is high time for it to intervene to prevent further bloodshed."
Clashes between Tibetan protesters and Chinese authorities occurred in recent days in Ganzi Prefecture, a mountainous area west of Sichuan Province.
The unrest comes after a string of self-immolations by Tibetan protesters in recent months and with the approach of the anniversary of an uprising against Chinese rule, which has been a flash point in the past.
The United States, which recognizes Tibet as an autonomous region of China, expressed concern about the situation.
"We are seriously concerned by reports of violence continuing, heightened tensions in the Tibetan area of China, including reports that security forces in Sichuan Province have been opening fire on protesters, killing some and injuring others," Victoria Nuland, a spokeswoman for the U.S. State Department, said Tuesday.
The Chinese government and international groups advocating Tibetan rights have offered differing versions of events this week in Ganzi, which Tibetans call Kardze. China has accused the rights groups of trying to "distort the truth" about the violence through "ill-intentioned hype."
The first clashes took place Monday in Luhuo County, known as Drango by Tibetans. Citing witnesses, rights groups like Free Tibet and the International Campaign for Tibet say that thousands of Tibetans had marched on government offices before the police opened fire into the unarmed crowd, killing two or three protesters and injuring dozens.
The reports, which could not be independently verified, contrasted with the account given by the Chinese state news agency.
A group of people, some with knives, damaged stores along a main street before throwing stones at the police and destroying two police vehicles and two ambulances, according to Xinhua news agency.
The violence left one of the marchers dead and four wounded, as well as five police officers wounded, according to the news agency. It did not mention the use of guns by the authorities.
Then on Tuesday, violence reportedly erupted in Seda County, which Tibetans call Serthar. Tibetan advocacy groups said that the Chinese security forces had shot dead between two and five protesters.
There was no immediate reaction from the Chinese authorities on the reports of violence in Seda.
"How long and how many tragic deaths are necessary before the world takes a firm moral stand?" said Sangay, who took over from the Dalai Lama last year as the political head of the Tibetan government-in-exile in Dharamsala, India. "Silence from the world community sends a clear message to China that its repressive and violent measures to handle tensions in Tibetan areas are acceptable."
The United States said it was keeping the pressure on China over the issue.
The violence comes ahead of the Tibetan New Year on February 22 amid high tensions following more than a dozen self-immolations by Tibetans in the past year.
For a fifth straight year, China will close Tibet to foreign tourists again this year from the Tibetan New Year festival until the anniversary of a deadly anti-government riot among Tibetans in March, according to regional travel agents.
CNN's Sumnima Udas, Jethro Mullen and Chi-Chi Zhang contributed to this report.