The victims were detained after police fired shots and tear gas on Aug. 12 into an unarmed group of demonstrators, who gathered to demand the release of a village leader who complained "against the mistreatment and harassment of Tibetans by the Chinese authorities," said the government-in-exile, in Dharamsala, India.
The demonstration occurred in the village of Shukpa, in Sichuan's Shiqu county.
Radio Free Asia, a Washington-based advocacy group, said dozens of protesters were detained and their injuries not treated. It added two died Sunday while in custody -- one a suicide, and three more, all related, died of what it termed "untreated gunshot wounds." The three ranged in age from 18 to 60 and were related to the village leader who was detained.
"It is not known when they died, but their bodies were handed over to their families on Monday," the administration in Dharamsala said.
There was no confirmation of the incident, or of the deaths, by Chinese authorities.
The province in southwestern China adjoins the Tibet Autonomous Region and is heavily Tibetan in population and culture. It is regarded as a center of anti-Beijing defiance, and the site of most of the 131 suicides by self-immolation, in protest of Chinese authority, in China since 2008.