HARBIN - Sixteen miners had been rescued and four others remained trapped underground in a coal mine accident in northeast China's Heilongjiang Province, the rescuers said Friday night.

Rescue workers broke through the tunnel around 9 p.m. Friday and assisted the 16 miners, whom they had established contact with, out of the shaft about 10 p.m., said Ren Shangyin, deputy head of the Junde Coal Mine where a rock outburst took place early Friday.

The rescued miners were immediately sent to two local hospitals and were in stable condition, according to medical staff from the hospitals.

Rescuers are trying to contact the other four miners who remain trapped.

Twenty miners were trapped in the Junde Coal Mine in the city of Hegang when the accident happened around 5:20 a.m. Friday.

The coal mine, with designed annual output capacity of three million tonnes of coal, is owned by the state-owned Heilongjiang Longmay Mining Holding Group.