Thousands of people defied a nighttime curfew to protest in Myanmar's largest city Yangon on Monday, with some 200 demonstrators being trapped for a period by security forces in the central part of the city, Reuters and other media reported.

The security forces pulled back from the Sanchaung district on Tuesday morning, enabling the demonstrators to disperse, Reuters said, citing an activist who had been in a building with about 15 to 20 others.

Anti-coup protesters block a street using bags of cement in preparation for clashes with military and police on March 5, 2021 in Yangon, Myanmar. (Getty/Kyodo)

Michelle Bachelet Jeria, the U.N. high commissioner for human rights, on Monday issued a statement calling for their immediate release, as did the U.S. and British embassies.

Security forces have conducted nighttime crackdowns across Myanmar. The military, which ousted the elected government of Aung San Suu Kyi in a coup last month, has taken control of universities, hospitals and public schools in major cities such as Yangon and Mandalay, and begun using the locations as bases.

Earlier Monday, three anti-coup protesters were shot dead by security forces, local media reported, as workers staged a general strike across the country and the military government moved to shut down independent local media outlets.

Two men were shot in the head in Myitkyina, capital of the northernmost Kachin State, when security forces opened fire on a crowd of hundreds of protesters, while the third person was shot in the chest in Phyarpon, a small town in the country's southwestern Ayeyarwady Region.

The military government on the same day revoked permission of five local private media outlets to publish, including major broadcasters Mizzima and DVB, and Myanmar Now, an online publisher widely respected for its powerful investigative reports.

More than 50 people have been killed by the security forces since the military seized power. It has insisted that it is using minimal force against protesters to keep order.

Besides restoration of civilian rule, the protesters are calling for the release of elected leaders, including Suu Kyi, who remain detained following the coup.