At least four Tibetans are reported to have been shot dead by Chinese police at a protest in Baiyu County in Sichuan Province. Thirty more were injured, with some in critical condition.

The shooting happened on August 17th, but reports have only just emerged.

According to Radio Free Asia, a group of Tibetans had gone to the Baiyu County headquarters on or around August 13th to express their concerns about increased gold mining damaging the environment. They claimed it was degrading the fertility of their farmland and destroying the local grassland habitat.

A source told Radio Free Asia that local officials rejected the Tibetans’ claims and detained them. Forty more Tibetans arrived at the Baiyu County offices to protest the detentions. They demonstrated for three days, until security forces opened fire on them.

Baiyu (or Palyul in Tibetan) saw some of the worst violence during the Chinese regime’s clampdown on Tibetan protests in 2008.