A powerful earthquake struck a rural, mountainous region of eastern Afghanistan early Wednesday, killing at least 920 people and injuring 600 others in the deadliest temblor in two decades, authorities said. Officials warned that the already grim toll would likely rise.

Information remained scarce on the magnitude 6.1 temblor near the Pakistani border, but quakes of that strength would be expected to cause severe damage in the remote area, where homes and other buildings are poorly constructed and landslides are common.

Rescue efforts are likely to be complicated since many international aid agencies left Afghanistan after the Taliban takeover of the country last year and the chaotic withdrawal of the U.S. military from the longest war in its history. Rescuers rushed to the area by helicopter.

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Neighboring Pakistan’s Meteorological Department said the quake's epicenter was in Afghanistan's Paktika province, some 50 kilometers (31 miles) southwest of the city of Khost. Buildings were also damaged in Khost province. The U.S. Geological Survey, which recorded the magnitude at slightly lower at 5.9, put the depth at just 10 kilometers (6 miles) — another factor that could increase the damage.

Footage from Paktika showed people being carried into helicopters to be airlifted from the area. Others were treated on the ground. One resident could be seen receiving IV fluids while sitting in a plastic chair outside the rubble of his home and still more were sprawled on gurneys. Some images showed residents picking through clay bricks and other rubble from destroyed stone houses.

The death toll, given by Afghan emergency official Sharafuddin Muslim, made it the deadliest quake since 2002, when a 6.1 magnitude temblor killed about 1,000 people in northern Afghanistan immediately after the U.S.-led invasion overthrew the Taliban government following the 9/11 attacks.

Earlier, the director-general of state-run Bakhtar news agency, Abdul Wahid Rayan, wrote on Twitter that 90 houses have been destroyed in Paktika and dozens of people are believed trapped under the rubble.

“We urge all aid agencies to send teams to the area immediately to prevent further catastrophe,” Bilal Karimi, a deputy spokesman for the Taliban government, wrote on Twitter.

In Kabul, Prime Minister Mohammad Hassan Akhund convened an emergency meeting at the presidential palace to coordinate the relief effort for victims in Paktika and Khost.

The “response is on its way,” the U.N. resident coordinator in Afghanistan, Ramiz Alakbarov, wrote on Twitter.

Pakistan’s Prime Minister Shahbaz Sharif in a statement offered his condolences over the earthquake, saying his nation will provide help to the Afghan people. At the Vatican, Pope Francis offered prayers for all those killed and injured and for the “suffering of the dear Afghan population.”

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In just one district of Khost province, the earthquake killed at least 25 people and injured over 95 others, local officials said.

Some remote areas of Pakistan saw reports of damage to homes near the Afghan border, but it wasn't immediately clear if that was due to rain or the earthquake, said Taimoor Khan, a disaster management spokesperson in the area.

The European seismological agency, EMSC, said the earthquake’s tremors were felt over 500 kilometers (310 miles) by 119 million people across Afghanistan, Pakistan and India.

Mountainous Afghanistan and the larger region of South Asia along the Hindu Kush mountains has long been vulnerable to devastating earthquakes.

In 2015, a major earthquake that struck the country’s northeast killed over 200 people in Afghanistan and neighboring northern Pakistan. In 1998, a 6.1 magnitude earthquake and subsequent tremors in Afghanistan’s remote northeast killed at least 4,500 people.