The Ta'ang National Liberation Army, which is currently in a ceasefire with the Myanmar military and controls the village near the Chinese border, said there had been fatalities, without saying how many.
Local news outlet Shwe Phee Myay News Agency said at least 55 people had died, including 25 women and 30 men, and that dozens more were wounded.
It published photos and videos showing smoke from the explosion and damaged buildings and debris in its aftermath.
"The Palaung State Liberation Front/TNLA expresses its deepest condolences to the families of those who lost their lives, were injured, and suffered damage as a result of the explosion," the group said in a Telegram post.
It said the explosion that took place at noon local time was being investigated and that anyone found responsible would be held accountable.
It added that relief, healthcare and rehabilitation for the families affected by the blast would be provided as soon as possible.
A rescue worker who rushed to the site of the blast told the Associated Press that 46 bodies, including six children, had been recovered by Sunday evening and taken for cremation.
The rescuer, who spoke on condition of anonymity for security reasons, said 74 injured people had been transported to the township hospital and rescue operations were continuing.
Another rescuer in Namhkam, who also spoke on condition of anonymity, said about 40 people were killed and more than 100 houses near the blast site were damaged.
with AP
