Muzaffarabad, Pakistan ? Thousands of people could die unnecessarily from disease, diarrhea and untreated injuries if a disaster-weary world doesn’t help quake-ravaged Pakistan, UNICEF’s chief warned during a helicopter tour of the region Sunday.

Ann Veneman said the window of opportunity to act is closing, with winter rolling rapidly toward the unforgiving Himalayan mountains. Forecasters are predicting a colder than usual winter, with up to 17 feet of snow in some places. Relief officials say some 800,000 quake survivors could face the frigid weather with absolutely no shelter.

“The fear is that we could lose thousands of people additionally to diarrhea, disease and injuries that are not treated,” Veneman told The Associated Press in an interview during the helicopter tour. “It’s absolutely urgent that as much aid gets in as possible. This is an area that will get much colder as the winter comes and the people are going to need shelter and blankets.”

Some 80,000 people are believed to have died in the 7.6-magnitude quake on Oct. 8, and 3.3 million have been left homeless. Half the victims are believed to be children, according to UNICEF.

Displaced Kashmiris, left homeless after the Oct. 8 earthquake, line up Sunday at an aid distribution center on a roadside outside of Muzaffarabad, Pakistan.

Despite dire warnings of a looming calamity, the United Nations has had difficulty raising money for the quake victims. As of Friday, it had received just 20 percent of the $550 million it needs for the next six months. Officials have warned that the shortfall could force U.N. helicopters to stop flying as early as this week.

UNICEF controls $62 million of the aid pledge, but has so far received just $13.5 million.

Veneman, a former secretary of agriculture in the Bush administration, joined a chorus of voices calling on the world to act.

“Without urgent action, large numbers of children could die needlessly,” she said, adding that she believed that aid has been slower to arrive because of the many natural calamities over the past year.

Zobaida Jalal, Pakistan’s minister of social welfare who accompanied Veneman on the trip, said the tragedy was unavoidable, but she called the current crisis a test of the world’s humanity.

“The earthquake was a natural calamity that nobody could do anything about, but if these people are allowed to die now, that would be more of a tragedy,” she said. “It will be on the consciences of many people and many governments forever.”