Chinese police also fired tear gas at those protesting Sunday in Biru county in the Tibet Autonomous Region and dozens were injured, Radio Free Asia said in its report Tuesday.
The report, which cited unnamed local and exiled Tibetan sources, could not be independently confirmed. Local Communist Party and government officials either could not be reached by phone or hung up shortly after answering.
The International Campaign for Tibet earlier reported that authorities had intensified the security presence in Biru county and nearby areas after residents refused orders to display Chinese flags to commemorate National Day on Oct. 1.
The ICT, a Tibetan rights group, said government work teams had been sent to Biru, known as Driru in Tibetan, ahead of the national holiday to compel local Tibetan residents to fly the flag as part of an intensified effort to enforce loyalty to the Communist Party.
In Sunday's unrest, protesters were calling for the release of a local resident, Dorje Draktsel, who was detained last week after participating in demonstrations against the flag order, the Radio Free Asia report said.
The self-proclaimed Tibetan government-in-exile based in India said it has received reports of the firing in Driru but had few details to provide. Spokesman Tashi Phuntsok said by phone that the exiled Tibetans had heard that some protesters were injured but did not know how many.
China has claimed Tibet as part of its territory for centuries while Tibetans say they were largely independent prior to the occupation by communist troops in 1950.
Many Tibetans say Beijing's economic policies in the Himalayan region have largely benefited only Chinese migrants and that they resent strict limits on Buddhism and Tibetan culture that the government imposes. China says it has made vast investments to boost the region's economy and improve the quality of life for Tibetans.
Meanwhile, in the northwestern Muslim region of Xinjiang, an official Chinese newspaper said authorities have detained more than 100 people from late June to the end of August for the spread of "religious extremism."
The detentions are the latest in an official campaign in Xinjiang to police the spread of ideas critical of Chinese government rule in addition to pouring troops into the restive region.
Xinjiang sees periodic outbreaks of anti-government and anti-Chinese violence, some of it inspired by resentment over economic marginalization by ethnic Han migrants who have flooded into the region in recent decades, along with restrictions on Uighur social and cultural life.
Associated Press writer Ashwini Bhatia contributed to this report in Dharamsala, India.