"Words of condemnation or concern are frankly ringing hollow to the people of Myanmar while the military junta commits mass murder against them", the United Nations special rapporteur for Myanmar, Mr Tom Andrews, said.
The EU delegation in Yangon called Saturday "a day of terror and dishonour", while the U.S. embassy said the security forces' actions were akin to "murdering unarmed civilians", adding "these are not the actions of a professional military or police force".
How have other leaders reacted?
This figure does not take into account the deaths which took place on Saturday however. Armed with battlefield weapons, the security forces appeared willing to shoot anyone they saw on the streets.More news: Canada assured vaccine exports from European Union won't be blocked
The Myanmar government has not responded to requests for comment on the civilian killings or on reports of the KNU's killing of soldiers at an army base.
UN Secretary-General Antonio Guterres wrote on Twitter: "The continuing military crackdown is unacceptable and demands a firm, unified & resolute global response".
The killings, reportedly of more than 100 people, show "that the junta will sacrifice the lives of the people to serve the few", Mr Blinken said.
The European Union's delegation to Myanmar said on Twitter: "This 76th Myanmar armed forces day will stay engraved as a day of terror and dishonour".
This statement comes after 114 civilians were killed across Myanmar on Saturday as the military junta continued to crackdown on peaceful protests.
She said the toll had risen to between 83 and 91 people killed along with hundreds of wounded.More news: Dominion Voting Systems sues Fox News for $1.6 bln over election claims
So far on Sunday, there were no reports of large-scale protests in Yangon or in the country's second city, Mandalay, which bore the brunt of the casualties on Saturday, Myanmar's Armed Forces Day.
Funeral services were also held on Sunday for some of the victims of Saturday's events.
Relatives of 13-year-old boy Sai Waiyan, who was shot Saturday playing outside his house in Yangon, cried over his casket on Sunday afternoon, local media reported. The move by such a large group of defense chiefs was unprecedented, he said, and came in response to growing alarm among Western-allied military organizations at the brazen targeting of unarmed civilian protesters and blatant human rights violations. Protestors in Insein, Yangon faced fire from military forces, where three people were killed.
About 3,000 villagers from Myanmar's south-eastern Karen state fled to Thailand yesterday, following air attacks by the army on an area held by ethnic armed group Karen National Union. Fatalities were reported in the cities of Yangon, Bago, Mandalay and surrounding regions.
"This movement against the military coup is not going to stop", said DW correspondent Dave Grunebaum.
'The role of the military in society is to protect its citizens, not to murder and terrorise them.More news: Covid vaccination: India administered 5.46 crore vaccine doses so far
In recent days the junta has portrayed the demonstrators as the perpetrators of the violence for their sporadic use of Molotov cocktails.