Myanmar has endured mass protests demanding the military release civilian leader Aung San Suu Kyi, who was detained on February 1 at the start of the coup.
Authorities have in response steadily stepped up its use of force, with tear gas, water cannon, rubber bullets and, increasingly, live rounds, AFP reported.
Sunday was the bloodiest day since the February 1 coup, with the UN saying that at least 18 protesters were killed across the country.
In the northwestern town of Kale on Tuesday, another rally turned violent when security forces opened fire on protesters, according to medics who witnessed events and treated those wounded.
"About 20 people were injured in a morning crackdown by police and soldiers in Kale," said a rescue worker, on condition of anonymity for fear of repercussions.
"Three... were hit by live rounds and are in critical condition," he said, adding that police had initially deployed tear gas and rubber bullets, before doubling back with live rounds.
The bloodshed came the same day as the funeral was held in Yangon, the commercial capital, for a 23-year-old student who died Sunday.
Protests also continued in several different neighborhoods of Yangon on Tuesday, with demonstrators wearing hard hats and wielding improvised home-made shields.
The continued unrest as foreign ministers from 10-member Association of Southeast Asian Nations bloc met virtually, including a Myanmar representative.
Indonesia's Foreign Minister Retno Marsudi on Tuesday urged Myanmar to "open its doors" to the bloc to resolve escalating tensions.
After meeting with other ASEAN foreign ministers, Retno also called for the release of political detainees and for democracy to be restored in Myanmar, while pledging that ASEAN countries would not break their non-interference pledge.
Ahead of the meeting, some regional powers broke with diplomatic traditions and issued unusually harsh rebukes to Myanmar's junta.
"We are appalled by the use of lethal force against civilians," Singapore's Foreign Minister Vivian Balakrishnan told the city-state's Parliament Monday.
"We call on the Myanmar military authorities to exercise utmost restraint," he added, while urging a "return to the path of democratic transition".
Since the 1 putsch, the junta has tightened its chokehold on communications, imposing nightly internet shutdowns and blocking certain social media websites.
More than 1,200 people have been arrested, charged and sentenced, according to Assistance Association for Political Prisoners monitoring group, of which some 900 are still behind bars.