Nepalese rescue volunteers stand on the rubble of the compound wall of the British Embassy in Kathmandu. Photograph: Prakash Mathema/AFP/Getty Images
A strong 6.9-magnitude earthquake has hit northeast India, killing at least 19 people, including three caught in a wall collapse at the British Embassy in neighbouring Nepal.
The quake was felt across a wide region after it struck the small, landlocked Himalayan state of Sikkim - which borders Nepal, Bhutan and Tibet - about 6:10pm (22:40 AEST) last night, according to the US Geological Survey.
The epicentre was just over 60km northwest of the Sikkim state capital Gangtok, where at least 60 people were injured and the town was plunged into darkness by a power cut after the quake.
"There is no electricity. Everybody is out on the road," Gangtok resident CK Dahal told a local television news channel.
"We all ran out of our houses, some even jumped out of their windows. You can see some buildings that have developed cracks," he added.
Tremors were felt in Nepal, Bhutan, Bangladesh and the Indian cities of Guwahati and Kolkata, as well as 1000km away in the Indian capital New Delhi.
In Nepal, police said three people were killed, including a motorcyclist and his eight-year-old daughter, when a wall collapsed at the British Embassy compound in the capital Kathmandu, 270km west of the epicentre.
"Another two died in a separate incident in eastern Nepal," national police spokesman Binod Singh said.
A budget debate in Nepal\'s parliament was stalled for 15 minutes while MPs leapt to their feet and fled the chamber as the entire building shook.
Telephone landlines to Sikkim, India\'s least populous state, were knocked out and mobile networks were swamped, making communication with the affected area difficult.
The quake was followed by two strong aftershocks, one with a magnitude of 6.1, and the death toll may rise as reports arrive from remote communities.
Sikkim Chief Secretary Karma Gyatso said five people had been killed and 60 injured in and around Gangtok as the result of mudslides, building collapses and falling debris.
"We have reports of dozens of collapsed houses, and roads to many towns have been blocked by landslides," Gyatso said.
The Press Trust of India news agency said that police rescued 15 foreign tourists in the north of Sikkim, a popular destination for trekkers, but it did not give their nationalities.
Nine other people died in India, including one reportedly killed in a stampede by panicked residents in Bihar state and four who were buried when a house fell down near Darjeeling.
In New Delhi, Prime Minister Manmohan Singh called an emergency meeting of the National Disaster Management Authority, and Cabinet Secretary Ajit Seth said that air force planes carrying rescue teams and relief supplies had been despatched to Sikkim.
Strong tremors were felt in Guwahati, the main city in Assam state, some 600km away, sending people running into the streets.
In Bhutan, buildings in the capital Thimphu were also rocked.
India\'s seven northeastern states, joined to the rest of the country by a narrow sliver of land, are located in an area of frequent seismic activity.