At least 128 people have been confirmed dead after the shallow 5.6-magnitude earthquake that struck a remote pocket of Nepal overnight, Reuters news agency said, citing officials.
"At least 100 have been injured," Karnali Province police spokesman Gopal Chandra Bhattarai told the AFP news agency on Saturday.
"The remoteness of the districts makes it difficult for information to get through."
The tremor hit the far west of the Himalayan country and was measured by the US Geological Survey at just 18 kilometres deep.
Videos and photos posted on social media showed locals digging through rubble in the dark to pull survivors from the wreckage of collapsed homes and buildings.
Mud houses were flattened or damaged as survivors crouched outside for safety, as the sirens of emergency vehicles wailed.
The quake was felt as far away as India's capital New Delhi, nearly 500 km from the epicentre 42 km south of Jumla.
"In our district, 26 people have died and many are injured," Jajarkot district chief Suresh Sunar told the AFP news agency.
"It is still night and it is difficult to get all the information," he added. "The toll might rise."
The district hospital was packed with residents bringing in injured victims.
At least 36 were dead and 85 injured in neighbouring Rukum West, according to that area's police chief, Namraj Bhattarai.
"We are working on rescue efforts," he said.
Major geological faultline
Nepal lies on a major geological faultline where the Indian tectonic plate pushes up into the Eurasian plate, forming the Himalayas, and earthquakes are a regular occurrence.
The government deployed security forces to help with rescue efforts.
"We have information that there have been human and physical damages in two districts because of the quake, and security forces have been mobilised for rescue work," said home ministry spokesman Nararyan Prasad Bhattarai.
Numbers were still unconfirmed, he added.
Nepalese Prime Minister Pushpa Kamal expressed "his deep sorrow over the human and physical damage caused by the earthquake".
Nearly 9,000 people died and more than 22,000 were injured in 2015 when a 7.8-magnitude quake struck Nepal, destroying more than half a million homes.
It damaged or destroyed nearly 8,000 schools, leaving almost one million children without classrooms.
Hundreds of monuments and royal palaces — including the Kathmandu Valley's UNESCO World Heritage sites — that had drawn visitors from around the world were destroyed, in a major blow to tourism.
Total economic losses from the disaster were estim ated at $7 billion.
