VORKUTA, February 26. /TASS/. Rescuers have so far failed to make contact with miners trapped in the Severnaya coal mine in Vorkuta, a Russian city north of the Arctic Circle, Russian Emergencies Minister Vladimir Puchkov told reporters on Friday.

The effort is underway to "examine all the potentially dangerous areas where people may be," Puchkov said. More than 480 people and 90 pieces of equipment are involved in the operation.

Rescuers study all the possibilities to monitor the situation inside the coal mine. "Step by step we start restoring life support systems," the emergencies minister said.

A methane outburst occurred at the mine at the depth of 780 meters on Thursday afternoon. Two explosions caused rock collapse and fire later occurred at the scene, the Vorkutaugol company that owns the mine said.

A total of 110 people were trapped underground and eight of them were directly at the accident scene. Some 80 miners were evacuated in the first hours. Eight of them sought medical assistance and four were hospitalized. Four miners were confirmed dead and the fate of 26 miners remains unknown.

Earlier in the day, 70 rescuers arrived in Vorkuta onboard an Il-76 plane from Kemerovo to boost the group involved in the rescue operation in the coal mine, the emergencies ministry’s press service said.