At a military parade on Saturday, the general who led the overthrow of Myanmar’s civilian government last month said the army was determined “to protect people from all danger.”

Before the day was over, the security forces under his command had shot and killed a 5-year-old boy, two 13-year-old boys and a 14-year-old girl. A baby girl in Yangon, Myanmar’s largest city, was struck in the eye with a rubber bullet, although her parents said she was expected to live.

The slain children were among dozens of people killed on Saturday as the security forces cracked down on protests across Myanmar, in what appeared to be one of the deadliest days since the Feb. 1 coup led by Senior Gen. Min Aung Hlaing, commander of the Tatmadaw, as the military is known. One news outlet, Myanmar Now, put Saturday’s death toll as high as 80.

“Today is a day of shame for the armed forces,” Dr. Sasa, a spokesman for a group of elected officials who say they represent Myanmar’s government, said in a statement.

a medal and a ceremonial sword.

Russia has been an important supplier of weapons to the Myanmar military, and as a permanent member of the United Nations Security Council it can be counted on, along with China, to block any attempt by the international body to impose sanctions on Myanmar.

The United States said on Thursday that it was putting its own financial sanctions on two military-owned conglomerates that control a large segment of Myanmar’s economy.

shots had been fired at its cultural center in Yangon, the American Center, on Saturday. The embassy said that no one was hurt and that it was investigating.

the Karen National Union said on Facebook that it had overrun and seized a Tatmadaw camp. The group posted photos of weapons it said it had seized, including what appeared to be machine guns and rocket-propelled grenades.

The Tatmadaw has fought for decades with various ethnic groups in Myanmar, including the Karen. Some opposition leaders hope that urban protesters, who are mainly from the majority Bamar ethnic group, can build a coalition with the ethnic groups to resist the Tatmadaw.

The widespread killings on Saturday came a day after military-run television threatened protesters with being “shot in the back and the back of the head” if they persisted in opposing military rule.

According to the Assistance Association of Political Prisoners, which has tracked arrests and killings since the coup, about a quarter of those killed before Saturday were shot in the head.

The killings on Saturday took place in more than two dozen cities across the country. Many of the victims were bystanders.

In Meiktila, a city in central Myanmar, 14-year-old Ma Pan Ei Phyu was at home when the security forces began shooting randomly in the neighborhood, said her father, U Min Min Tun. The family did not hear a shot, and they didn’t realize that she had been killed until she fell to the floor. She had been hit in the chest.

In Yangon, 13-year-old Maung Wai Yan Tun was playing outside when the police and soldiers arrived. Scared, he ran away and was shot, his mother told the online news outlet Mizzima. The family went to recover his body, but finding it surrounded by security forces, they dared not approach.