BANGKOK — Myanmar government troops rounded up villagers, some believed to be children, tied them up and slaughtered them, according to a witness and other reports. An opposition leader said the civilians were burned alive, as repression of resistance to a de facto coup takes an increasingly brutal turn.

A video of the aftermath of Tuesday’s assault — apparent retaliation for an attack on a military convoy — showed the charred bodies of 11 people, lying in a circle amid what appeared to be the remains of a hut.

Outrage spread both inside and outside Myanmar as the graphic images were shared on social media of the assault, which Human Rights Watch said was similar to other recent attacks — and looked like it was meant to be discovered.

“This incident is quite brazen, and it happened in an area that was meant to be found, and seen, to scare people,” spokesperson for the group, Manny Maung, said.

“Our contacts are saying these were just boys and young people who were villagers who were caught in the wrong place at the wrong time,” she added.

The rights group called Thursday for the international community to ensure that commanders who gave the order are added to targeted sanctions lists, and more broadly, efforts are stepped up to cut off any source of funding to the military, which seized power Feb. 1.

A witness told The Associated Press that about 50 troops marched into the village of Done Taw in the country’s northwest at about 11 a.m. Tuesday, seizing anyone who did not manage to flee.

“They arrested 11 innocent villagers,” said the witness, who described himself as a farmer and an activist and spoke on condition of anonymity because he fears for his safety.

He did not see the moment of their killing but said he believed they were burned alive, as did other people who spoke to Myanmar media.

He later saw the charred remains — and was present when the images were taken. The images themselves could not be independently verified.

The government has denied that it had any troops in the area.

Opposition spokesperson, Dr. Sasa, said in a statement that the attack bore “witness to the military’s escalation of their acts of terror.”

“The sheer brutality, savagery, and cruelty of the these acts shows a new depth of depravity, and proves that, despite the pretense of the relative détente seen over the last few months, the junta never had any intention of deescalating their campaign of violence,” said Sasa, who uses one name and is the spokesperson for Myanmar’s underground National Unity Government, which says it is the country’s only legitimate administration.

He said a military convoy had been hit by a roadside bomb and troops retaliated first by shelling Done Taw, then rounding up anyone they could capture.

“They were lashed together, tortured, and ultimately burned alive,” he said, adding that the victims ranged in age from 14 to 40.

The military ouster of the elected government of democracy leader Aung San Suu Kyi was initially met with nonviolent street protests, but after police and soldiers responded with lethal force, violence escalated as opponents of military rule took up arms.

The witness who spoke to the AP said that those captured in Tuesday’s attack were not members of the locally organized People’s Defense Force, which sometimes engages the army in combat. He said they were as members of a less formally organized village protection group but did not give a reason for the soldiers’ assault.

Other witnesses cited in Myanmar media said the victims were members of a defense force.

In recent months, fighting has been raging in northwestern areas, where the army has unleashed greater force against the resistance than in urban centers.

U.N. spokesman Stephane Dujarric expressed deep concern at the reports of the “horrific killing of 11 people” and strongly condemned such violence, saying “credible reports indicate that five children were among those people killed.”

Dujarric reminded Myanmar’s military authorities of their obligations under international law to ensure the safety and protection of civilians and called for those responsible “for this heinous act” to be held accountable.

As of Wednesday, he said security forces have killed more than 1,300 unarmed individuals, including more than 75 children, since the military takeover on Feb. 1.

In seizing power, the military claimed there was massive fraud in the 2020 election that saw Suu Kyi’s National League for Democracy win in a landslide. The military said that justified the takeover under a constitution that allows it to seize power in emergencies — though independent election observers did not detect any major irregularities.

On Monday, Suu Kyi was convicted on charges of incitement and violating coronavirus restrictions and sentenced to two years in prison. The court’s action was widely criticized as a further effort by military rulers to roll back the democratic gains of recent years.

By Auther