The quake, which was felt across northern India, western Nepal and southern China, brought down houses on thousands of people as they slept.
The first tremor, measuring 6.8 on the Richter scale, came at 12.35am yesterday morning.
Officials expect the number of casualties to rise because the tremors devastated houses in Chamoli, a semi-urban area of 50,000 people, and the neighbouring district of Rudraprayag. Both were close to the epicentre in the Garhwa hills.
Police said rescue efforts were hampered by a series of post-quake landslides in the region, which is dotted with the villages of subsistence hill-farmers.
The earthquake appeared to be the strongest in the Himalayan foothills in 94 years. In April 1905, an earthquake measuring 7.2 on the Richter scale killed thousands in neighbouring Himachal Pradesh state. In 1991, at least 1,600 people died when the area was hit by a quake measuring 6.6 on the scale.