Story highlights The death toll rises to 68 in India, 7 in China, 6 in Nepal

The Indian government deploys helicopters to assist

70% of the homes are destroyed in a county in southwestern China, official says

Three earthquakes hit the region Sunday evening

The death toll from a powerful weekend earthquake that rocked parts of India, China and Nepal climbed to 81 Tuesday, emergency officials said.

India's Home Ministry said 68 people have died in three northern states -- 50 in Sikkim, 12 in West Bengal and 6 and Bihar.

The government pressed the National Disaster Response Force into action, deploying helicopters to survey damage and airlift food packets. State governments have set up relief camps.

In China, at least seven people died and 24 others were injured in Yadong County in the Tibet Autonomous Region, the state-run Xinhua news agency reported.

Damage is widespread, said Dianzin Namgyai, a local secretary of the Communist Party of China..

"Nearly 70% of the county's houses have been damaged," he said.

Nepal's National Emergency Operation Center reported a death toll of six on Tuesday, one fewer than previous reports. No explanation for the change was given.

A series of three quakes struck the region in quick succession Sunday evening.

A magnitude 6.9 earthquake was followed by two at magnitudes 4.8 and 4.6. All three occurred within an hour and 15 minutes, the U.S. Geological Survey said. The India Meteorological Department said the quakes were 6.8 magnitude, 5.7 magnitude and 5.3 magnitude.

That quake's epicenter was about 42 miles from the city of Gangtok, the capital of Sikkim, and 169 miles east of Kathmandu in Nepal, according to the USGS.