China is the world's largest coal producer, and deadly accidents in mines are common
The accident occurred Thursday when a cable supporting a mining cage caught fire, causing the rig to tumble down into a state-operated coal mine in northeast China's Heilongjiang province, Xinhua news agency said.
An operation to extract the trapped miners from the wreckage was launched at the time but rescue workers could not reach them until Monday, finding them all dead, Xinhua said.
The mine, the Dongrong Second Mine under the Longmay Mining Holding Group, is located near the city of Shuangyashan.
Two welders have been detained by police over "allegedly serious violations" of safety regulations, Xinhua said.
The mine's manager also has been suspended from his post, it quoted the local government as saying.
China is the world's largest coal producer, and deadly accidents in mines are common.
In December, explosions in two separate coal mines in the Inner Mongolia region and in Heilongjiang killed at least 59 people, according to state media reports.
Thirty-three miners were killed in a colliery explosion in October in the southwestern municipality of Chongqing, and in September at least 18 were killed in a mine blast in the northwestern Ningxia region.