By Michael Bristow
BBC News, Hezuo, Gansu province, China
We managed to avoid police checkpoints on the road leading south to Hezuo on Wednesday.
China is deploying extra security forces inside Tibet
Hezuo is outside Tibet, but mostly inhabited by Tibetans, and in an indication of just how tense the situation here is, the streets were virtually empty when we drove through just before dusk.
Most shops were closed, even though it was early evening, and police cars were patrolling the streets. Some roads were blocked off by the security forces.
After nightfall, the streets became completely deserted; convoys of police vehicles drove up and down with their lights flashing.
A van with a police escort also drove slowly through the streets broadcasting a message in both Tibetan and Chinese.
"The riots in Tibet were organised by a small group of people who engaged in beating, smashing, robbing and burning," the announcement said.
"This has brought serious harm to people's lives, work and property. The Dalai clique deliberately conspired to seriously destroy social order and stability," it added.
People should abide by the law, the announcement went on.
Sangay Tashi, of the Free Tibet Campaign, said there had been protests across Maqu County, south of Hezuo, but also in Gannan, over recent days.
Tibet: Protests began in Lhasa on 10 March, dozens reported dead over weekend
Gansu: Unrest spread to Machu, where Tibetan government in exile says 19 died, and near Hezuo, where protesters were filmed tearing down Chinese flag
Sichuan: Reports of riots and casualties in Aba, and of unrest in other locations
Qinghai: Other unrest reported
One Tibetan told him a convoy of 25 trucks with armed Chinese troops entered the county on Wednesday, he told the BBC from Dharamsala, India.
"The person who reported this also saw tanks as well," he added.
With security tight in the area, and the Chinese reluctant to give out information, these claims are extremely difficult to verify.
Television footage obtained by Canadian journalists also showed marauding Tibetans on horseback 20km (12 miles) south of Hezuo on Tuesday.
They tore down the Chinese flag at a school and replaced it with a Tibetan one.
Earlier on Wednesday, we also saw a train carrying about two dozen military vehicles, including trucks and four-wheel drives, on the rail line that leads to Tibet.
The words China's People's Armed Police Rapid Reaction Force were written on the side of one of the vehicles, spotted on the Qinghai-Gansu border.
It is clear the Chinese are deploying extra security forces both inside Tibet and in other areas in western China as the tension continues.
China says it is fully capable of restoring order following the outbreak of protests in both Tibet and other areas of China inhabited by Tibetans.
But the situation in Hezuo suggests the protests are continuing.