More than a hundred soldiers from the Myanmar Army's Light Infantry Division 66 traveled from Demoso to Hpruso, where they engaged individuals driving on the Moso-Koi Ngan Road.

[2] Four members of the Karenni National People's Liberation Front (KNPLF), an ethnic armed organisation then under Border Guard Forces,[3] arrived on the scene and attempted to negotiate for the release of the detainees.

Upon securing the scene on December 25, the KNDF found the victims' bodies burned to ashes or charred beyond recognition, both in their vehicles and on the ground beside them.

[2] On December 27, the KNDF reported that over thirteen individuals were missing after the incident, including eight people from Loikaw who worked in a petrol station and three others believed to be on the roadway where the massacre occurred.

[2] Ten days after the massacre, the Karenni State Police held a press conference, announcing that there were 31 bodies, five female and 26 male, as well as three large garbage bags of human remains turned to ash.

According to Myanmar's state government, their soldiers killed an unknown number of people in seven vehicles from Koi Ngan that failed to stop at a security checkpoint.

"[12] The United Nations Undersecretary-General for Humanitarian Affairs, Martin Griffiths, said it was a "horrific" incident and that the Government of Myanmar must investigate the massacre.

[13] The American embassy in Myanmar also condemned the massacre, deeming it "barbaric" and demanding that the government "immediately cease its indiscriminate attacks in Karen State and throughout the country and ensure the safety of all civilians in line with international law.”[14][15] In the aftermath of the massacre, the European Union called for international arms embargo on Myanmar’s military regime.

[17] In August 2022, Human Rights Watch reported that Tin Soe, a brigadier general who had been based in the Eastern Command during the massacre, had been trained by the Japan Self-Defense Forces.