KATHMANDU, Nepal (AP) — A powerful earthquake struck Nepal Saturday, killing at least 71 people as the violently shaking earth collapsed houses, leveled centuries-old temples and triggered avalanches in the Himalayas. It was the worst temblor to hit the poor South Asian nation in over 80 years.

At least 30 people died in neighboring countries where the quake was felt including 20 in India.

The quake with a preliminary magnitude of 7.8 struck before noon and was most severely felt in the capital as well as the densely populated Kathmandu Valley. A magnitude-6.6 aftershock hit about an hour later, and smaller aftershocks continued to ripple through the region for hours.

Dozens of people with injuries were being brought to the main hospital in central Kathmandu.

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.

The earthquake also shook several cities across northern India, and was felt as far away as Lahore in Pakistan, Lhasa in Tibet, and in Dhaka, Bangladesh.

The Home Ministry said in a statement that 71 people were killed in Nepal. It did not give details. Twenty people were killed in India, six in Tibet and two in Bangladesh, officials and media reports there said. China said two Chinese citizens were killed on the Nepal-China border.

A senior mountaineering guide, Ang Tshering, said an avalanche swept the face of Mt. Everest after the earthquake, and government officials said at least 30 people were injured.

Tshering of the Nepal Mountaineering Association said the avalanche apparently occurred between the Khumbu Icefall, a rugged area of collapsed ice and snow, and the base camp where most climbing expeditions have their main camps. (backslash)

While details are unclear with communications limited to the Everest region, Tshering said the avalanche did not appear to have hit the base camp itself.

The quake's epicenter was 80 kilometers (50 miles) northwest of Kathmandu, and it had a depth of only 11 kilometers (7 miles), which is considered shallow in geological terms. The shallower the quake the more destructive power it carries.

As the ground began to shake, several buildings collapsed in the center of the capital, the ancient Old Kathmandu, including centuries-old temples and towers, said resident Prachanda Sual.

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

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

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. The economy of Nepal, a nation of 27.8 million people, is heavily dependent on tourism, principally trekking and Himalayan mountain climbing.

Robin Trygg, a climber, was in a basecamp on the Cho Oyu mountain at an altitude of 5,600 meters (18,480 feet) when he felt the quake.

"We were sitting in the tent and drinking tea when all of a sudden the earth began shaking. We didn't understand what happened," he told the Swedish news agency TT by telephone.

In Kathmandu, dozens of people were 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 had hooked up some patients to IV drops in the parking lot, or were giving people oxygen.

The U.S. Geological Survey revised the magnitude from 7.5 to 7.9 but then lowered it to 7.8. It said the quake hit at 11:56 a.m. local time (0611 GMT) at Lamjung. It was the largest shallow quake since the 8.2 temblor off the coast of Chile on April 1, 2014.

An earthquake's power increases by 10 times with each increase in the number of its scale. A magnitude 7 quake is capable of widespread and heavy damage while an 8 magnitude quake can cause tremendous damage.

This means Saturday's earthquake — the same magnitude as the one that hit San Francisco in 1906 — was 22 times more powerful than the 7.0 quake that devastated Haiti in 2010.

Saturday's earthquake was the same magnitude as the one that devastated San Francisco in 1006 and 22 times more intense than the

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 meters (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 45 kilometers (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. AP reporters in Indian cities of Lucknow in the north and Patna in the east also reported strong tremors.

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.

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Naqvi reported from New Delhi. Associated Press writer Munir Ahmed in Islamabad and Jan M. Olsen in Copenhagen contributed to this report.