Two killed in Tibet-linked clash
A policeman and the suspect were shot dead in the incident in Dari County, Qinghai province, Xinhua said.
The attempted arrest was linked to a riot in the area last month by "insurgents seeking Tibetan independence", the news agency said.
Anti-China protests began in Tibet's main city, Lhasa, on 10 March and quickly spread to surrounding areas.
China says at least 19 people were killed by rioters, but Tibetan exiles say that dozens of people were killed by Chinese security forces.
Tibet and the surrounding provinces where the protests took place have been closed to foreigners since the unrest.
Xinhua said that a "handful of people" incited herders to riot in Hongke Town, Dari County on 21 March.
"After a month-long investigation, the police moved on Monday to arrest the suspected leader. The suspect resisted arrest and gunfire broke out," it said.
"The officer was killed in the gun battle... and other officers returned fire, killing the suspect."
The agency named the dead officer as Lama Cedain, an ethnic Tibetan officer from the local public security bureau.