The death toll from the massive South Asia earthquake soared above 42,000 as the first trickle of humanitarian aid began to flow into the region, authorities said.
Islamic Relief spokesman Waseem Yaqhoob told CNN he thought the death toll would reach "80,000, maybe more."
"This could get very close to tsunami levels," he said. "It's horrific. It really is terrible."
Meanwhile, 120 metric tons of ready-to-eat food arrived Tuesday, enough to feed 240,000 people for five days, a World Food Programme spokesman told CNN.
Another 80 million metric tons of food aid is in the pipeline, Amjad Jamal said. (World boosts quake aid effort)
But he acknowledged the need was great and said appeals were being made to the international community for additional donations of food, supplies and money.
In parts of northern Pakistan, India and the disputed region of Kashmir, the scene is one of utter devastation: entire villages destroyed, millions left homeless and survivors using anything they can to wade through mountains of rubble searching for survivors, food and clean water, according to CNN.
Even with many far-flung areas still not reached, the death toll has hit 41,000 in Pakistan alone, with another 1,239 dead in India and one reported death in Afghanistan, officials have said.
In Pakistan, survivors are becoming more frustrated over the pace of relief efforts, with some resorting to looting.
As many as 5 million people have been left homeless, living in the open air and freezing temperatures since the quake.
Officials in both Pakistan and India have defended relief efforts, saying blocked roads and a lack of helicopters have prevented rescue teams areas in mountainous terrain.
A strong autumn cold front descended on central Asia Tuesday, spawning severe storms and hindering search teams as they continued their frantic efforts to find survivors.
Pakistani presidential spokesman Maj. Gen. Shaukat Sultan told CNN some areas had been "virtually impossible to reach" via land routes, but that rescue teams were on their way "to the most affected areas."
"Convoys are now moving during night as well as during the day to reach the area. The scale of the rescue is now going to be much more than what we could manage through the helicopters only," he said.
India's Home Secretary V.K. Duggal said Monday that relief has been sent to most areas, but some remote patches in Uri, Kupwara and Baramulla have not yet been covered.
"As road accessibility improves, we hope to reach these villages by (Tuesday)," Duggal told a news conference in New Delhi.
Reporting from the Pakistani capital of Islamabad, CNN's Andrew Stevens said there was a "lot of anger" over the relief efforts.
"There is a general feeling more needs to be done," Stevens said, adding the government says it cannot deal with the sheer scale of the disaster.