Local officials said a mob attacked a police station in Seda county on Tuesday, Xinhua news agency reported.
Tibetan activist groups said security forces fired on people protesting against religious repression.
On Monday, at least two other protesters were killed in neighbouring Draggo county.
Accounts of violence in the area differ and are difficult to verify. Foreign media, including the BBC, are barred from the area.
Xinhua news agency said that police used force in Seda “after efforts involving persuasion and non-lethal weapon defence failed to disperse the mob”. Its report said one “rioter” was killed.
But Tibet campaign groups dispute this version of events and say two people were killed. UK-based Free Tibet says that the town is now under curfew, citing local residents.
A monk from the monastery in Draggo told the Associated Press on Tuesday in a telephone interview that 33 people were being treated for injuries at the compound.
The US State Department has expressed serious concern about the reports, urging the Chinese government “to engage in a constructive dialogue with the Dalai Lama or his representatives as a means to address Tibetan concerns”.
But Chinese foreign ministry spokesman Hong Lei said on Tuesday that “overseas secessionist groups” were trying to discredit the government.