A strong earthquake shook northeastern India and Nepal on Sunday night, killing at least 9 people, damaging buildings and sending lawmakers in Nepal's capital running into the streets.
The quake, with a preliminary magnitude of 6.9, was felt across northeast India including the capital of New Delhi. It triggered at least two aftershocks of magnitude 6.1 and 5.3, Indian seismology official R.S. Dattatreyan said. He warned more aftershocks were possible.
At least four people in India's Sikkim state were killed and an unspecified number of people were injured, state police Chief Jasbir Singh told The Associated Press. Nepal's government said five people died and dozens were hurt there.
The full extent of damage was not immediately known because the region is sparsely populated with many living in remote areas which were cut off by mudslides triggered by the quake, Singh said.
TV stations reported buildings collapsed and sidewalks cracked in Sikkim's state capital of Gangtok, 42 miles (68 kilometers) southeast of the quake's epicenter. The Indo-Tibetan Border Police said two of its buildings had collapsed in Gangtok.
Rescuers were working overnight to search for anyone pinned under fallen buildings in the city, which has a population of 50,000, Singh said.<
"We have sounded a high alert. Police are on the streets in Gangtok and other major towns," he said.
Electricity and some phone service was interrupted in the area.
Power lines snapped in the West Bengal cities of Darjeeling and Kalimpong, which "are now in total darkness," state Chief Minister Mamata Banerjee said.
Prime Minister Manmohan Singh offered to send troops to help, and summoned the National Disaster Management Authority for an emergency meeting. The air force sent five planes to help with rescue efforts.
In neighboring Nepal and Bangladesh, the quake sent residents rushing out of their homes, offices and shopping centers.
In Nepal's capital of Katmandu, members of parliament who were debating the national budget ran out of the assembly hall into a parking area. They returned 15 minutes later and resumed their session.
The quake was also felt as far as the Indian capital, with New Delhi residents also rushing out of shaking buildings
Earlier, Sikkim Chief Secretary Karma Gyatso told the CNN-IBN news channel that there were initial reports of one child having been killed in the quake, but there was no immediate confirmation.
Residents of the state capital Gangtok said large cracks had developed in some buildings.
The US Geological Survey said the epicentre of the quake, which struck at around 6:10pm (1240 GMT), was located just over 60 kilometres (40 miles) northwest of Gangtok.
"It was a massive earthquake. We have alerted the armed forces and the paramilitary," Gyatso said.
Telephone lines to Gangtok were temporarily knocked out and mobile networks were quickly swamped, making communication with the affected area difficult.
Gangtok resident C.K. Dahal told CNN-IBN that the city had been plunged into darkness by a power cut immediately after the quake, which lasted for around 20 seconds.
"There is no electricity. Everybody is out on the road," Dahal said.
"We all ran out our houses, some even jumped out of their windows. You can see some buildings that have developed cracks," he added.
Manish Sharma, a doctor attending a conference in Gangtok, told the NDTV news channel that guests in his hotel had all run for the doors as soon as the first tremors were felt.
"I am standing in front of the legislative assembly of Gangtok and I can see one of the outer buildings... the upper side is in two parts," Sharma said.
"I can see light coming out of that particular portion. It has not collapsed but it is in two parts, one part has moved aside," he said. "The police are trying to calm people down."
Powerful tremors were felt in Guwahati, the main city in neighbouring Assam state, some 600 kilometres away, sending panicked residents running into the streets.
The quake also shook buildings in the Nepalese capital Kathmandu, 270 kilometres west of the epicentre, where traffic came to a standstill and hotels and bars were evacuated.
Hundreds of anxious tourists and office workers waited for news in car parks and on the streets as the seasonal monsoon rain lashed down.
Three people were injured as a wall in the British Embassy compound in central Kathmandu collapsed, the Himalayan Times reported on its website.
In Bhutan, the capital Thimpu was rocked by the tremors.
"Our wooden house is safe. Jars fell in kitchen, books fell from shelf," Thimpu resident Aby Tharakan, a media consultant, said in a message posted on the microblogging website Twitter.