A deadly attack by government troops in eastern Myanmar on civilians carried out on Christmas Eve included two Save the Children charity staff members, the non-profit organization said on Tuesday.

“With profound sadness, we confirm two of our staff are among the burnt bodies found in Myanmar after an attack by the military on Xmas Eve. Both new fathers working on education for children,” the organization said in a statement posted on social media. “The UN Security Council must convene & take action to hold those responsible to account.”

Saying he was “horrified” by the results of the attack, United Nations (UN) Undersecretary-General for Humanitarian Affairs Martin Griffiths said in a statement on Sunday, “I condemn this grievous incident and all attacks against civilians throughout the country, which are prohibited under international humanitarian law.”

“I call upon the authorities to immediately commence a thorough and transparent investigation into the incident so that perpetrators can be swiftly brought to justice,” added Griffiths.

“Moreover, I call upon the Myanmar Armed Forces and all armed groups in Myanmar to take all measures to protect civilians from harm,” he said.

According to the organization, the two staff members of the Save the Children were returning to their office after conducting humanitarian activities nearby when they were caught up in the attack in Kayah state.

Inger Ashing, Save the Children’s chief executive, said in a released statement, “Violence against innocent civilians including aid workers is intolerable, and this senseless attack is a breach of International Humanitarian Law.”

“This is not an isolated event. The people of Myanmar continue to be targeted with increasing violence, and these events demand an immediate response,” Ashing added.

The Myanmar military, which seized power in February arrested the de facto president Aung San Suu Kyi and several other government officials claiming election fraud. The Junta has faced numerous peaceful protests since their coup. Trying to hand onto power, the military has responded with deadly force and killed at least 1,400 civilians in the past year.   

State media claimed that the troops were in a battle with armed terrorists but made no mention of civilians. In a story posted by the AP, local villagers said the civilians were fleeing the fighting between government forces and resistance fighters when they were caught on the road. The state-run Myanma Alinn newspaper said that during the fighting, those resistance fighters drove in “suspicious” vehicles and attacked security forces after refusing to stop. They claimed the vehicles were destroyed in a fire.

Social media in Myanmar was flooded with images of two burned-out trucks and a car on a highway in Hpruso township in Kayah state, with the charred remains of bodies inside. which further fueled outrage against the military. 

On Sunday, the U.S. embassy in Myanmar said it was appalled by the “barbaric attack in Kayah state that killed at least 35 civilians, including women and children”.

“We will continue to press for accountability for the perpetrators of the ongoing campaign of violence against the people of Burma,” it said in a statement posted on Twitter.