BANGKOK, Sept. 28 — Myanmar’s armed forces appeared to have succeeded today in sealing tens of thousands of protesting monks inside their monasteries, but they continued to attack bands of civilian demonstrators who challenged them in the streets of the main city, Yangon.

Witnesses and diplomats reached by telephone inside Myanmar said troops were now confronting and attacking smaller groups of civilians around the city, sometimes running after them through narrow streets, sometimes firing at protesting groups.

“Today has been quieter than previous days, meaning far fewer protesters came out, but the military is being very quick to use violence, tear gas, guns and clubs to break it up,” said the chief diplomat at the United States Embassy, Shari Villarosa.

Diplomats said there was no way to estimate the numbers of dead and wounded in Yangon or other cities, but they said it was certainly far higher than the number the junta has reported.