Tibetans in China's southwestern Sichuan province say at least two Tibetans were shot dead Tuesday when police fired on crowds of anti-Chinese protesters, as authorities tightened security in Lhasa and Beijing.

Authorities in the Tibetan capital began arresting hundredsof people in the wake of anti-Chinese protests over the weekend as adeadline passed for those involved in the marches, demonstrations, andrioting to "surrender" to police.

Violence spreads from Tibet through neighboring parts of China as anti-Chinese protesters take to the streets in Sichuan, Gansu, and Qinghai provinces, with large crowds of Tibetans marching on government buildings.