A powerful earthquake has rocked Nepal, wrecking buildings, injuring dozens of people and causing an unknown number of deaths, eyewitnesses say.
The quake measured 7.9 and struck an area between the capital Kathmandu and the city of Pokhara, the US Geological Survey said.
Tremors were felt across the region, as far afield as Pakistan, Bangladesh and neighbouring India.
A Nepali minister said there had been "massive damage" at the epicentre.
"We need support from the various international agencies which are more knowledgeable and equipped to handle the kind of emergency we face now," Information Minister Minendra Rijal.
Several buildings, including the landmark Dharahara tower, were reduced to rubble in Kathmandu.
The tower was turned into a stump, with several feared dead among its ruins.
Injured people have been brought to the main hospital. Reuters news agency put the initial death toll at four, including casualties at the tower.
After the earthquake struck, concerned residents came out into the streets. Mobile phones and other communications have been disrupted.
"It was very scary. The earth was moving... I am waiting for treatment but the [hospital] staff are overwhelmed," a labourer who injured his arm in a collapsing wall told AP.
Indian authorities are responding. "We are in the process of finding more information and are working to reach out to those affected, both at home and in Nepal," Prime Minister Narendra Modi tweeted.
Aftershocks could still be felt across the region sometime after the initial quake.
Mountaineer Alex Gavan tweeted that the quake caused an avalanche on Mount Everest.
In 2011, a deadly earthquake killed at least five people in Nepal. Kathmandu was all but destroyed in the devastating earthquake of 1934.
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