About 70 other people were injured in the explosion that took place about noon in the village of Kaungtup, in Namhkam township.
The area, located about 3km south of the Chinese border, is under the control of the Ta'ang National Liberation Army, an ethnic armed group which has engaged in sporadic fighting against Myanmar's central government.
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.
Myanmar media outlets, including Shan State's online Shwe Phee Myay news agency, reported death tolls ranging from 50 to 55.Â
They published photos and videos showing smoke from the explosion and damaged buildings and debris in its aftermath.
Chinese state broadcaster CCTV reported the explosion caused multiple deaths and injuries, with many residential houses being severely damaged, but did not give figures.
It said that according to preliminary investigations, the blast occurred at a site where large quantities of explosives used for mining operations were stored.
Local authorities are providing relief, medical care and resettlement assistance to affected residents, the report said.
The Ta'ang National Liberation Army, or TNLA, said in a statement released on its Telegram channel that gelignite had been stored by the group's economic department for use in mining and stone quarrying sites, and that an investigation into the cause of the explosion is underway.
Gelignite is widely used in mining and rock blasting but can become highly unstable over time and if poorly stored.
The Ta'ang National Liberation Army, or TNLA, is a member of the rebel Three Brotherhood Alliance, and has controlled the Namhkam area since the alliance and its allies launched a major offensive against the military in northeastern Myanmar in late 2023.
The alliance members and other ethnic armed groups have long fought for increased autonomy.
The TNLA signed a ceasefire with Myanmar's military following China-mediated talks in October last year but relations remain tense.
