Tibetan high school students protested in the streets of at least two towns in western China this week to mark the anniversary of an uprising against Chinese rule, and some have been detained, residents said on Thursday.
The demonstrations appear to be the first unrest in tightly controlled Tibetan areas at a highly sensitive time. March is the anniversary of both spiritual leader the Dalai Lama's flight into exile decades ago, and a uprising across the areas in 2008.
Beijing has stepped up its security presence and promised to pour extra cash into development to calm the restive and strategically vital border region.
But critics say if China does not address Tibetan concerns about the loss of their culture and heritage, stability will remain elusive.
At least 20 teenagers were taken into custody by police in the remote western town of Hezuo on Wednesday, shortly after a larger group began a protest, a hotel clerk there said.
Hezuo is in a Tibetan corner of Gansu province.
She declined to give her name, or comment on the motive for the protest, saying "only themselves know".
On March 14, dozens of teenagers also took to the streets of Machu, also in Gansu, chanting pro-Tibetan slogans, said a supermarket manager who himself is Han Chinese. He was not clear if anyone was arrested.
Information for this report was provided by Reuters.