Myanmar pro-democracy activists pledged on Thursday to hold more demonstrations after the United Nations said 38 people had been killed in the most violent day of unrest since last month's military coup.
Police and soldiers opened fire with live rounds on Wednesday with little warning, witnesses said, a day after neighbouring countries had called on the junta to show restraint.
"We know that we can always get shot and killed with live bullets but there is no meaning to staying alive under the junta so we choose this dangerous road to escape," activist Maung Saungkha told Reuters.
"We will fight the junta in any way we can. Our ultimate goal is to remove the junta system from the roots," said Maung Saungkha, who said his General Strike Committee of Nationalities group planned to hold a protest on Thursday.
Other activists said on social media at least two more demonstrations were planned in Yangon, as supporters of elected government leader Aung San Suu Kyi pressed for her release from detention and recognition of her victory in November elections.
Five fighter jets made several low passes in formation over the second city of Mandalay early on Thursday, residents said, in what appeared to be a show of military might.
UN special envoy on Myanmar, Christine Schraner Burgener, said in New York that Wednesday was the "bloodiest day" since the February 1 coup with 38 deaths, bringing the total toll to more than 50 as the military tries to cement its power.
A rights group and some media have given different numbers of wounded and killed after Wednesday's violence. The dead included four children, an aid agency said. Media reported that hundreds of protesters were arrested.
A spokesman for the ruling military council did not answer telephone calls seeking comment.
Suu Kyi's National League for Democracy party said in a statement that flags would fly at half mast at its offices to commemorate the dead.
Schraner Burgener said she warned Myanmar deputy military chief Soe Win that the military was likely to face strong measures from some countries and isolation in retaliation for the coup.
"The answer was: 'We are used to sanctions, and we survived'," she told reporters. "When I also warned they will go (into) isolation, the answer was: 'We have to learn to walk with only few friends'."
The UN Security Council is due to discuss the situation on Friday in a closed meeting, diplomats said.
UN Special Rapporteur Tom Andrews said the "systematic brutality" of the military was again on display.
"I urge members of the UN Security Council to view the photos/videos of the shocking violence being unleashed on peaceful protesters before meeting," he said on Twitter.
US State Department spokesman Ned Price said the United States was "appalled" by the violence and was evaluating how to respond.
The United States has told China it expects it to play a constructive role, he said. China has declined to condemn the coup, with Chinese state media calling it a "major cabinet reshuffle".
The European Union said the shootings of unarmed civilians and medical workers were clear breaches of international law. It also said the military was stepping up repression of the media, with a growing number of journalists arrested and charged.