Airstrikes by Myanmar's military on Tuesday killed as many as 100 people, including many children, who were attending a ceremony held by opponents of army rule, said a witness, a member of a local pro-democracy group and independent media.

The military is increasingly using airstrikes to counter a widespread armed struggle against its rule, which began in February 2021 when it seized power from the elected government of Aung San Suu Kyi. More than 3,000 civilians are estimated to have been killed since then by security forces.

A witness told The Associated Press that a fighter jet dropped bombs directly into a crowd of people who were gathering at 8 a.m. for the opening of a local office of the country's opposition movement outside Pazigyi village in Sagaing region's Kanbalu township. The area is about 110 kilometers (70 miles) north of Mandalay, the country's second largest city.?

About half an hour later, a helicopter appeared and fired at the site, said the witness, who asked not to be identified because he feared punishment by the authorities.?

Initial reports put the death toll at around 50, but later tallies reported by independent media raised it to about 100. It was impossible to independently confirm details of the incident because reporting is restricted by the military government.?

“I was standing a short distance from the crowd when a friend of mine contacted me on the phone about the approach of a fighter jet,” the witness said. “The jet dropped bombs directly on the crowd, and I jumped into a nearby ditch and hid. A few moments later, when I stood up and looked around, I saw people cut to pieces and dead in the smoke. The office building was destroyed by fire. About 30 people were injured. While the wounded were being transported, a helicopter arrived and shot more people. We are now cremating the bodies quickly.”

About 150 people had gathered for the opening ceremony, and women and 20-30 children were among the dead, he said, adding that those killed also included leaders of locally formed anti-government armed groups and other opposition organizations.

'This heinous act by the terrorist military is yet another example of their indiscriminate use of extreme force against innocent civilians, constituting a war crime,” the opposition National Unity Government said in a statement. The NUG calls itself the country's legitimate government, in opposition to the army. The office being opened Tuesday was part of its administrative network.

The military government's spokesperson, Maj. Gen. Zaw Min Tun, acknowledged in a statement phoned to state television MRTV that the ceremony had been attacked, but accused anti-government forces in the area of carrying out a violent campaign of terror. He said the People's Defense Forces — the armed wing of the National Unity Government -- had terrorized residents into supporting them, killing Buddhist monks, teachers and other people, while the military sought peace and stability. He said there was evidence the attack had set off secondary blasts of explosives hidden by the People's Defense Forces around the site.

In response to accusations of abuses, the military government often accuses pro-democracy forces of terrorism. But analysts for the United Nations and non-governmental organizations have gathered credible evidence of large-scale human rights abuses by the army, including the burning of entire villages and displacement of more than a million people, triggering a humanitarian crisis.

The death toll from Tuesday's air attack, if confirmed, could be the highest in more than two years of civil conflict that began when the army seized power in 2021. As many as 80 people were killed last October in another government air attack in northern Myanmar on an anniversary celebration of the Kachin ethnic minority's main political organization, which is also battling the military government.

Myanmar has been in turmoil since the army takeover triggered widespread popular opposition. After peaceful demonstrations were put down with lethal force, many opponents of military rule took up arms, and large parts of the country are now embroiled in conflict.

The army has been conducting major offensives in the countryside, where it has faced some of the toughest resistance in Sagaing, in Myanmar's historic heartland. The resistance forces have no defense against air attacks.

In videos of the devastated village seen by AP, survivors and onlookers stumble through the area of the attack amid clouds of thick smoke, with only the skeleton frame of one building still standing in the distance. The videos could not immediately be verified but matched other descriptions of the scene.

Some motorbikes remained intact while others were reduced to their frames or buried under tree branches. In one area, two victims lay close together, one of whom had only one arm still attached.

Another victim lay face down in a small grove by the roadside. A few meters (yards) away, a small torso missing at least one limb could be seen.?

In January, Myanmar's top leader told the military it needs to take decisive action against those opposed to army rule. Senior Gen. Min Aung Hlaing said at a military parade on Armed Forces Day that those who condemned his government showed indifference to violence committed by its opponents.

Resistance forces have been able to prevent the military from taking firm control of large areas of the country, but have a great disadvantage in weapons, particularly in countering air attacks.

Critics of the military government advocate banning or limiting the sale of aviation fuel to Myanmar to cripple the military's advantage in air power. Many Western nations have imposed arms embargoes on the military government, and the United States and Britain recently enacted new sanctions targeting individuals and companies involved in supplying jet fuel to Myanmar.

The human rights group Amnesty International said in a statement Tuesday that “The relentless air attacks across Myanmar highlight the urgent need to suspend the import of aviation fuel. Amnesty reiterates its calls on all states and businesses to stop shipments that may end up in the hands of the Myanmar Air Force.”?

It also urged the U.N. Security Council to "push through effective actions to hold the Myanmar military accountable, including by referring the situation in the country to the International Criminal Court.”?