BEIJING (AP) -- Angry protesters set shops ablaze and gunfire was reported in Tibet's regional capital Friday as the largest demonstrations in two decades against Chinese rule turned violent just months ahead of the Beijing Olympics.
The protests, in their fifth day and led by monks supporting Tibet's exiled spiritual leader, the Dalai Lama, threatened to cast a shadow over China's efforts to portray a unified and prosperous nation in the run-up to the games.
Protesters set shops and police vehicles on fire in Lhasa, state media and witnesses said. The U.S. Embassy in Beijing warned Americans to stay away, saying it had "received firsthand reports from American citizens in the city who report gunfire and other indications of violence."
The protests are the largest and most sustained in Lhasa since Beijing crushed a wave of pro-independence demonstrations in 1989. Since then, China has invested in the region, vilified the Dalai Lama and tried to weed out his supporters among the influential Buddhist clergy.
But Tibetans inside and outside the country have sought to use the Olympic Games' high profile to call attention to their cause. Beijing has accused the Dalai Lama - who many Tibetans consider their rightful ruler - of trying to sabotage the games.
A Lhasa resident, who asked to be unnamed for fear of government reprisal, said military police had closed all roads leading to the city center.
"The situation is quite serious. There's a curfew in the city and I can see military police block all the roads to the center of the city. Nearly all the stores and shops are closed," the resident said.
A Tibetan woman who has family in the city said protesters were setting fires.
"The monks are still protesting. Police and army cars were burned. There are people crying," said the witness, who also requested anonymity for fear of government reprisal. "Hundreds of people, including monks and civilians are in the protest."
Tensions in the Tibetan capital have increased in recent days. The city's three biggest monasteries were sealed off by thousands of soldiers and armed police in a government crackdown against the protests, the U.S.-funded Radio Free Asia reported Friday.
Monks at the major Sera Monastery launched a hunger strike Thursday to demand that armed police withdraw from the monastery grounds and detained monks be released, RFA reported.
At the Drepung Monastery, two Buddhist monks are in critical condition after attempting to commit suicide by slashing their wrists, RFA said, citing authoritative sources.
Also believed to be under watch is a third monastery, Ganden. The London-based International Campaign for Tibet said monks from the Ganden monastery mounted protests Thursday, becoming the last of the three historically important monasteries known as the "Three Pillars of Tibet" to join in the demonstrations.
Tourists were mainly staying off the streets and were being warned away from all the monasteries, said one tourist staying at a Lhasa hotel.
"The Red Army is downtown. It's not safe to walk around. All the major monasteries are closed," said the tourist, who refused to give her name or her nationality. "Tourists don't feel comfortable walking around because police are all over."
The Chinese government was trying to keep foreigners from getting in, with travel agents in China and neighboring Nepal refusing to issue the special permits needed to visit the region.
It is extremely difficult to get independent verification of events in Tibet since China maintains rigid control over the area. Journalists are rarely granted access except under highly controlled circumstances.
Officials who answered phones at police and Communist Party offices in Tibet on Friday said they had no information about the violence and refused to comment.
Beijing maintains that Tibet is historically a part of China. But many Tibetans argue the Himalayan region was virtually independent for centuries and accuse China of trying to crush Tibetan culture by swamping it with Han people, the majority Chinese ethnic group.
The protests by the Buddhist monks began Monday, the anniversary of the failed 1959 Tibetan uprising against Beijing rule.
In northern India, meanwhile, organizers said more than 100 Tibetan exiles began a two-week detention after police arrested them during a march to their homeland to protest China's hosting of the Olympics.
March coordinator Tenzin Palkyi said Friday the exiles were being kept in detention in a state-run hotel while authorities investigate the charges of threatening the "peace and tranquility" of the region.
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