Two members of charity Save the Children are missing after Myanmar government troops rounded up villagers, some believed to be women and children, before fatally shooting more than 30 of them and burning the bodies.

Photos of the aftermath of the purported Christmas Eve massacre in eastern Mo So village, where refugees were sheltering from an army offensive, spread on social media in the country and fuelled outrage against the military that took power in February. The accounts could not be independently verified.

The photos showed the charred bodies of over 30 people in three burned-out vehicles.

A villager who said he went to the scene told The Associated Press the victims had fled the fighting between armed resistance groups and Myanmar’s army near Koi Ngan village, which is just beside Mo So, on Friday.

He said they were killed after being arrested by troops while heading to refugee camps in the western part of the township.

Save the Children said two of its staff who were travelling home for the holidays after conducting humanitarian response work in a nearby community were “caught up in the incident and remain missing”.

“We have confirmation that their private vehicle was attacked and burned out,” the group added in a statement. “The military reportedly forced people from their cars, arrested some, killed others and burned their bodies.”

The government has not commented on the allegations, but a report in the state-run Myanma Alinn daily newspaper on Saturday said the fighting near Mo So broke out on Friday when members of ethnic guerrilla forces, known as the Karenni National Progressive Party, and those opposed to the military drove in “suspicious” vehicles and attacked security forces after refusing to stop.

The newspaper report said they included new members who were going to attend training to fight the army, and that the seven vehicles they were travelling in were destroyed in a fire. It gave no further details about the killings.