SOUTHWEST HARBOR — A local documentary filmmaker who has been filming a documentary about sherpas working on Mount Everest had left the mountain only hours before a deadly earthquake hit Nepal.

The powerful quake struck Nepal Saturday, killing at least 906 people across a swath of four countries as the violently shaking earth collapsed houses, leveled centuries-old temples and triggered avalanches on Mt. Everest. It was the worst tremor to hit the poor South Asian nation in over 80 years.

Alison Hudson has been shooting film and conducting interviews at Base Camp on Everest and had flown out of Lukla, an alpine town in the mountain’s shadow, only hours before the temblor struck.

She flew to Kathmandu, Nepal’s capital, where she weathered multiple aftershocks.

“Landed in Kathmandu this morning and four hours later stood in a doorway as the whole world shook,” Hudson wrote on her Facebook page. “Four hours of aftershocks. Am safe and hoping others are as well. Saddened at the loss of life and of culture.”

She said aftershocks were still occurring. A building where she was staying in Kathmandu was evacuated but Hudson indicated that she managed to retrieve all her film footage, her laptop computer and her camera.

The Associated Press reported that at least 876 people were confirmed dead in Nepal, according to the police. Another 20 were killed in India, six in Tibet and two in Bangladesh. Two Chinese citizens died at the Nepal-China border. The death toll is almost certain to rise, said deputy Inspector General of Police Komal Singh Bam.

It was a few minutes before noon when the quake, with a preliminary magnitude of 7.8, began to rumble across the densely populated Kathmandu Valley, rippling through the capital Kathmandu and spreading in all directions — north toward the Himalayas and Tibet, south to the Indo-Gangetic plains, east toward the Brahmaputra delta of Bangladesh and west toward the historical city of Lahore in Pakistan.

A magnitude-6.6 aftershock hit about an hour later, and smaller aftershocks continued to jolt the region for hours. Residents ran out of homes and buildings in panic. Walls tumbled, trees swayed, power lines came crashing down and large cracks opened up on streets and walls. And clouds of dust began to swirl all around.

“Our village has been almost wiped out. Most of the houses are either buried by landslide or damaged by shaking,” said Vim Tamang, a resident of Manglung village near the epicenter. He said half of the village folks are either missing or dead. “All the villagers have gathered in the open area. We don’t know what to do. We are feeling helpless,” he said when contacted by telephone.

Meteorologists forecast rain and thunderstorms were forecast for Saturday night and Sunday.

Within hours of the quake, hospitals began to fill up with dozens of injured people. Many came to the main hospital in central Kathmandu. Among them was Pushpa Das, a laborer, ran from the house when the first quake struck but could not escape a collapsing wall that injured his arm.

“It was very scary. The earth was moving … I am waiting for treatment but the (hospital) staff is overwhelmed,” he said, gingerly holding his right arm with his left hand. As he spoke dozens of more people showed up with injuries, mostly from falling bricks.

Following the quake, Kathmandu’s international airport was shut down.

While the extent of the damage and the scale of the disaster are yet to be ascertained, the quake will likely put a huge strain on the resources of this poor country best known for Everest, the highest mountain in the world, and its rich Hindu culture. The economy of Nepal, a nation of 27.8 million people, is heavily reliant on tourism, principally trekking and Himalayan mountain climbing.

A mountaineering guide, Ang Tshering, said an avalanche swept the face of Mt. Everest after the earthquake, and government officials said at least 8 climbers were killed and 30 injured. Their nationalities were not immediately known.

Carsten Lillelund Pedersen, a Dane who is climbing the Everest with a Belgian climber Jelle Veyt, said on his Facebook page that they were at Khumbu Icefall , a rugged area of collapsed ice and snow close to base camp at altitude 16,500 feet when the earthquake hit.

He wrote on his Facebook that they have started to receive the injured, including one person with the most severe injuries who sustained many fractures.

“He was blown away by the avalanche and broke both legs. For the camps closer to where the avalanche hit, our Sherpas believe that a lot of people may have been buried in their tents,” he wrote in English. “There is now a steady flow of people fleeing basecamp in hope of more security further down the mountain”

The U.S. Geological Survey put the magnitude of the quake at 7.8. It said the quake hit at 11:56 a.m. local time at Lamjung, about 50 miles northwest of Kathmandu. Its depth was only 11 kilometers seven miles, the largest shallow quake since the 8.2 temblor off the coast of Chile on April 1, 2014.

The shallower the quake the more destructive power it carries, and witnesses said the trembling and swaying of the earth went on for several minutes.

A magnitude 7 quake is capable of widespread and heavy damage while an 8 magnitude quake can cause tremendous damage. This means Saturday’s quake — with the same magnitude as the one that hit San Francisco in 1906 — was about 16 times more powerful than the 7.0 quake that devastated Haiti in 2010.

“The shallowness of the source made the ground-shaking at the surface worse than it would have been for a deeper earthquake,” said David A. Rothery, professor of planetary geosciences at the Open University in Milton Keynes, north of London.

A major factor in the damage was that the buildings were not built to be quake-proof. An earthquake this size in Tokyo or Los Angeles, which have building codes for quake resistance, would not be nearly as devastating.

The power of the tremors brought down several buildings in the center of the capital, the ancient Old Kathmandu, including centuries-old temples and towers.

Among them was the nine-story Dharahara Tower, one of Kathmandu’s landmarks built by Nepal’s royal rulers as a watchtower in the 1800s and a UNESCO-recognized historical monument. It was reduced to rubble and there were reports of people trapped underneath.

Hundreds of people buy tickets on weekends to go up to the viewing platform on the eighth story, but it was not clear how many were up there when the tower collapsed. Video footage showed people digging through the rubble of the tower, looking for survivors.

The Kathmandu Valley is densely populated with nearly 2.5 million people, and the quality of buildings is often poor.

In Kathmandu, dozens of people gathered in the parking lot of Norvic International Hospital, where thin mattresses were spread on the ground for patients rushed outside, some wearing hospital pajamas. A woman with a bandage on her head sat in a set of chairs pulled from the hospital waiting room.

Doctors and nurses hooked up some patients to intravenous drips in the parking lot, or were giving people oxygen.

A Swedish woman, Jenny Adhikari, who lives in Nepal, told the Swedish newspaper Aftonbladet that she was riding a bus in the town of Melamchi when the earth began to move.

“A huge stone crashed only about 20 yards from the bus,” she was quoted as saying. “All the houses around me have tumbled down. I think there are lot of people who have died,” she told the newspaper by telephone. Melamchi is about 30 miles northeast of Kathmandu.

Nepal suffered its worst recorded earthquake in 1934, which measured 8.0 and all but destroyed the cities of Kathmandu, Bhaktapur and Patan.

The sustained quake also was felt in India’s capital of New Delhi and several other Indian cities.

India’s Prime Minister Narendra Modi called a meeting of top government officials to review the damage and disaster preparedness in parts of India that felt strong tremors. The Indian states of Uttar Pradesh, Bihar and Sikkim, which share a border with Nepal, have reported building damage. There have also been reports of damage in the northeastern state of Assam.

Pakistan Prime Minister Nawaz Sharif offered “all possible help” that Nepal may need.