BEIJING — In a fresh illustration of growing turmoil among ethnic Tibetans in Sichuan Province, three livestock herders have set themselves on fire to protest what they saw as political and religious repression at the hands of the Chinese authorities, according to a Tibetan rights group and an ethnic Tibetan living in Beijing.

The latest cases bring the total self-immolations by ethnic Tibetans over the past year to 19. They were also apparently the first by lay people, rather than current or former members of the clergy, suggesting that self-immolation may be gaining popularity as a form of dissent. The self-immolations took place Friday in a remote village in Seda County, once a center of Buddhist teaching, but reports did not surface until the weekend because the government had cut off Internet and telephone connections to the area, said Tsering Woeser, a Tibetan poet in Beijing.

She said that one of the three men had died and that the two others, believed to be about 30 and 60 years old, were severely injured.

The Chinese government has sealed off a number of counties in the region and intensified security in an attempt to curtail the largest outbreak of unrest among ethnic Tibetans since the 2008 riots in Tibet’s capital, Lhasa, and elsewhere.