A Tibetan mother of three has died after setting herself on fire in Sichuan province, two reports say.
The woman, in her 30s, set herself on fire outside a monastery in Aba county, Radio Free Asia and Free Tibet said.
Aba county has been at the heart of a series of self-immolations involving Tibetans in apparent protest against Chinese rule.
On Sunday, two men set themselves on fire in Lhasa, the first incidents in the Tibetan capital.
One of the men died while the other "survived with injuries", Xinhua news agency said.
Radio Free Asia reports that hundreds of Tibetan residents in Lhasa have been rounded up following the immolations, citing unidentified sources.
Foreign media are banned from the area, making reports difficult to verify.
But one resident contacted by AFP news agency said mobile phone signals had been blocked and police were checking people's identities on the streets, the agency said.
The woman who set herself on fire in Aba county on Wednesday was identified as a mother of two daughters and a son. She died at the scene, the reports said.
More than 30 Tibetans - mostly young monks and nuns - have set themselves on fire since March 2011.
Most of the incidents have take place in ethnically Tibetan areas outside Tibet.
China's leaders blame the Dalai Lama, the Tibetans' exiled spiritual leader, for inciting the self-immolations and encouraging separatism.
He rejects this, and both activist groups and the Tibetan government-in-exile say the self-immolations are protests against tight Chinese control of the region and religious repression.