BEIJING — A nun set herself on fire in the past week in a Tibetan area of western China to protest Chinese rule and to call for the return of the Dalai Lama from exile, according to two pro-Tibet advocacy groups.

The nun, Yeshi Khando, is believed to have died because of the intensity of the fire. The death could not be confirmed because the police took her away after dousing the flames with fire extinguishers, said the groups, which had spoken with people in the area where the self-immolation occurred on Wednesday.

Yeshi Khando, who was in her 40s and was from Nganggang Nunnery, set herself ablaze near a monastery in the Kardze area of Sichuan Province, known in Chinese as Ganzi. She was the second woman to set herself on fire this year and the 138th Tibetan to do so since 2009 in Tibetan regions ruled by China, according to the International Campaign for Tibet, an advocacy group based in Washington.

The protesters acted largely out of anger and frustration at what they call the Chinese occupation of their homeland, according to the groups, which are based outside China.