MUZAFFARABAD, Pakistan – With snow falling on parts of Kashmir, the U.N.’s emergency relief chief said yesterday that time was running out for many hungry, homeless survivors of a massive earthquake and urged aid agencies to speed up efforts in remote villages.

The plea came as aid workers struggled to reach remote areas and hours after an aftershock jolted parts of Pakistan, panicking people who had survived last weekend’s devastating temblor and forcing a rescue team to suspend efforts to save a trapped woman. She died before the rescuers returned to the precarious rubble.

The U.N. undersecretary general and emergency relief coordinator, Jan Egeland, flew by helicopter to the hard-hit Kashmiri city of Muzaffarabad, where he said there was an urgent need to get food, medicine, shelter and blankets to millions of people. The U.N. estimates 2 million people are homeless ahead of the fierce winter in the Himalayan region.

The death toll was believed to be more than 35,000 and tens of thousands were injured. India has reported more than 1,350 deaths in the part of Kashmir that it controls.

“I fear we are losing the race against the clock in the small villages” cut off by blocked roads, Mr. Egeland said. “I’ve never seen such devastation before. We are in the sixth day of operation, and every day the scale of devastation is getting wider.”

The American military in Afghanistan loaded cargo planes with food, tarpaulins and other emergency aid to drop by parachute over areas of Pakistan, officials said. The first plane was expected to leave Friday morning loaded with 10 tons of aid, said American military Sergeant First Class Rick Scavetta.

Trucks with aid from dozens of countries choked the roads up to the crumbling towns of Kashmir, but access to some areas remained blocked because of landslides and people in many remote areas where there are no roads were still in desperate straits five days after the temblor struck.

Underscoring the difficulty, Action-Aid International in Pakistan said some of its workers had to get out of their truck and walk in one area because of bad roads and traffic jams.

“The problem is that people are facing a shortage of time,” said Shafqat Munir, a spokesman for the group. “It’s cold, raining. People are without shelter. They have food, clothes, blankets, but tents are a problem.”

The 5.6-magnitude aftershock was centered 85 miles north of Islamabad, near the epicenter of Saturday’s 7.6-magnitude quake that demolished whole towns, mostly in Kashmir and northwestern Pakistan. The aftershock shook buildings, but no significant damage in the already demolished region was reported.