Rescuers brought in bulldozers, ambulances and helicopters in a massive effort to reach victims stuck in the frigid snow along the 12,700-feet-high Salang Pass, which links the Afghan capital Kabul with the northern city of Mazar-i-Sharif.
Search-and-rescue teams recovered the bodies of 24 people but said they feared 40 others remain trapped and may have also died, Interior Minister Hanif Atmar said at a news conference in Kabul. About 2,500 people were rescued from their snowbound vehicles, including more than 400 injured.
"Twenty-four bodies have been recovered so far, but the fear is that there could be up to 40 more still buried and unfortunately, they might have died already," he said. "That's the best estimate we have at this moment."
The avalanches struck Monday, burying vehicles along several miles of road under heavy snow. Atmar said that the highway tunnel had not been closed off earlier because there had been little warning.
"It happened all of a sudden and it took us by surprise," he said.
Military helicopters were dropping food packages to people stuck on snow-blocked roads, Interior Ministry spokesman Zemerai Bashary said. Earlier, Afghan reports said some 300 cars and buses were trapped on the mountain pass.
Afghan and coalition forces evacuated about 430 injured, with 180 taken by coalition helicopters to Bagram Airbase for medical treatment, said Defense Minister Gen. Abdul Rahim Wardak.
Atmar said authorities were unable to locate the parents of 24 children who had been evacuated and were being treated for injuries at local hospitals.
Some of the injured were taken to the Charikar Hospital in Parwan province. One injured eyewitness, Abdul Shakor, told Associated Press Television he saw more than 100 vehicles still trapped by snow.
"We cannot exactly say how many people have been killed. We opened (the door of) one Toyota car; there were five dead bodies inside and we brought them to the hospital with the help of police," he said.
Some 500 Afghan soldiers were mobilized to join about 400 police and others in rescue efforts. The international coalition contributed four Chinook helicopters, while the army sent two choppers, several ambulances and several bulldozers, the Afghan National Army said.
Suhrab Ali Safari, acting public works minister, told The Associated Press in a phone interview from Salang a that strong snowstorm overnight triggered a major avalanche that covered about 2 miles of road.
"Unfortunately, it has blocked the road completely. We're working to clear it from both sides, north and south," he said.
Safari said there had been a series of smaller avalanches in the area in recent weeks.
"Everybody is trying to rescue the people who are stuck in the avalanche. But while we're clearing one part of the road, the storm covered another part of the road again. It's very difficult," he said.
In a statement, President Hamid Karzai ordered the ministries of public works, defense and disaster control to "use all possible means to get the roads unblocked and rescue those trapped and stranded in the heavy snow."
He also expressed condolences to the families of the victims who were killed or injured.