Thousands of terrified survivors of a Himalayan earthquake that killed 81 people and rattled parts of India, Nepal and China crowded Tuesday into shelters and relatives' homes or stayed out in the open for fear of aftershocks.

Soldiers used dynamite and earthmovers to clear landslides on highways through the steep valleys linking the worst-hit northeastern Indian state of Sikkim to the rest of India. They managed to clear a path to Mangan, closest to the epicenter of Sunday's 6.9-magnitude quake, but many other communities remained cut off and authorities fear the death toll could rise once rescuers reach them.

Indian army helicopters ferried rescuers and dropped food and supplies to still-inaccessible villages in Sikkim, a sparsely populated and almost entirely mountainous region that was an independent protectorate before becoming an Indian state in 1975.

Residents of the state, which borders Nepal, Bangladesh, Bhutan and the Chinese region of Tibet, have been spooked by at least five aftershocks since Sunday, with the strongest a magnitude 5.3.

Dawa Lendup Lepcha, 25, a university student in Gangtok, the capital of Sikkim, said that even though the room he rents was not badly damaged, he was too nervous to stay there alone and moved in with a cousin.

"Even now we feel scared. If a car makes a loud sound or there is some other sudden noise I feel very scared," he said.

Thousands of others moved out of their homes in Gangtok and the neighboring villages and took shelter in the open grounds of a university building and a soccer stadium. Many were sleeping outside, huddling under blankets to ward off the cold. Nighttime temperatures have been about 17 degrees Celsius (62 fahrenheit).

"The damage to houses is substantial. Many thousands of houses have collapsed while others have suffered structural damage," said Amit Patro, editor of the English language Sikkim Express newspaper.

Fearing his own home wasn't safe, Patro moved with his mother, wife and two children to a friend's house.

"I don't know how long we will camp with friends. For a few more days at least, till I can convince my family that it's safe to move back," he said.

The quake killed at least 50 people in Sikkim and caused extensive damage to homes and buildings, said the state's top official, Karma Gyatso.

Another 12 people were killed in West Bengal and six others in Bihar, India's Home Secretary R. K. Singh told reporters. The earthquake also killed six people in Nepal and seven in Tibet.

Singh said rescue efforts were being hampered by heavy rain and landslides which had cut off large swaths of Sikkim.

Lepcha said he had only managed to speak with his family in northern Sikkim twice since Sunday's earthquake and while his relatives were safe, he said there were few details because the phone connections were very erratic.

The region has been hit by major earthquakes in the past, including in 1950 and 1897.