Soldiers and police pulled victims from rubble as night closed in and the number of victims climbed to 35 in the northeastern Indian state of Sikkim, the epicentre of Sunday night's quake felt more than miles away in Delhi.
At least seven died in Bihar state, south of Sikkim, while six died in the Indian state of West Bengal.
People in Sikkim's main city, Gangtok, sat on roadsides under umbrellas in the heavy rain and prepared for another chilly night - reluctant to go home for fear of aftershocks.
It has been raining for four straight days in parts of Sikkim. The temperature in the quake zone was about 8 degrees Celsius and will drop overnight.
Shops, businesses and offices were closed in Gangtok and neighbouring areas, another resident said. Many towns remained without electricity. Water supplies were scarce because of burst pipes and telephone communication was patchy.
The quake was felt in five countries including Bangladesh and Buddhist kingdom Bhutan.
Outside India, at least eight people died in Nepal, three of them when a wall at the British Embassy in Kathmandu collapsed on a car and a motorcycle. Seven died and hundreds were made homeless in Tibet, Chinese news agency Xinhua said.
More than a thousand Chinese soldiers were sent to help rescue efforts near the border.
Several hundred rescue workers and medics deployed by New Delhi were expected to arrive in Sikkim in the evening after soldiers cleared a landslide blocking the road from the nearest airport, 100 km away.
More than a thousand people fled damaged homes to government shelters in Gangtok. More than 100 people were injured, while hundreds of tourists, Indian and foreign, were stranded for hours on the main road out of the state to West Bengal in the south.
The quake shook buildings as far away as New Delhi in India and Bangladesh.
Several earthquakes have hit north and east India this year, but none has caused major damage or injuries.
In 2001, a devastating earthquake in the western state of Gujarat killed at least 19,700 people and caused damage in neighbouring Pakistan. In 1934, an estimated 10,000 people died when a quake devastated Nepal and India's Bihar state.
