"These areas, near the epicentre of the earthquake, are totally damaged. The roads from Gangtok to Mangan are blocked by massive landslides on at least 14 places," Army officials said following an aerial survey in the area.
The earthquake has left a trail of devastation damaging roads, houses, and other structures, uprooting mobile phone towers and snapping communication and power lines.
At least 41 people have been killed in the earthquake in Sikkim. Twenty-two people travelling in a bus went missing since last evening in the North district of Sikkim.
The North district headquarters of Mangan, located 65 km from Gangtok, seems to be totally devastated, officials said.
Both the routes to Mangan are cutoff by landslides and developed huge cracks following the earthquake. Efforts are being made to provide relief and rescue operations to the affected people in this area through helicopters, officials said.
Food packets have been dropped in the inaccessible areas of the state. Army troops, NDRF teams and disaster management authorities are working round-the-clock to clear the debris and open roads. Relief efforts have been hampered by torrential rain and landslides in most areas of the state.
A team of NDRF has been trying to move through Singhtham to reach Mangam and provide relief material to the affected people.
A PTI correspondent visiting earthquake-hit areas of Sikkim reported that people are still in a state of panic.
People are so scared that they are not entering their houses which have developed cracks or have got tilted after the earthquake. Many people were found sitting on roadsides, public places and near temples.
Tourists are yet to get over the shock. They have not yet been able to leave Gangtok and other places of the state as the roads are either damaged or blocked by landslides.
"We can return only after the roads open. We are still in shock and cannot forget the moment when the earth shook heavily. Most of the time we are staying outside," Joy Basu, who came from from Sodepur near Kolkata with his family, said.
Power and telephone lines have been restored in Gangtok. But the fringe areas of the town are enveloped in darkness and cut off from the rest of the world. All telephone connections outside Gangtok are still out of service.