Hundreds of quake survivors lined up outside a field hospital Tuesday to seek treatment for chest infections and other cold-related ailments after a blast of freezing rain hit northern Pakistan, health workers said.

Weather conditions improved in Pakistan's portion of Kashmir, allowing two helicopters to leave from the main city of Muzaffarabad for the first time in two days, said Pakistan's army, which has been delivering winterized tents, clothes, food and other aid to survivors.

Scores of people — many parents carrying children with respiratory infections — lined up for treatment at the hospital in Muzaffarabad, one of the areas worst-hit by the Oct. 8 quake that killed more than 80,000 people and left 3.5 million homeless.

Cold rain pelted the quake zone Sunday and Monday, and 2 feet of snow fell in Kashmir and northwestern Pakistan since Saturday, making conditions in tents "very bad," said Dr. Abdul Hafeez Kardar, head of Pakistan Islamic Medical Association field hospital.

"We are receiving a high number of people, especially children suffering from cold-related diseases, particularly acute respiratory infections," he added. "They need better protection from the cold."

He said about 600 people — about half of them children — had been treated since Monday, and some were suffering from bronchitis and pneumonia. He said 12 had been hospitalized.

The U.N. estimates 2.5 million people are living in tents below 5,000 feet, and as many as 400,000 others are in higher areas where it is feared that snow and rain will make it harder for helicopters and trucks to reach them.

Pakistan army spokesman Maj. Farooq Nasir said soldiers were moving from camp to camp, helping re-erect or replace tents that had collapsed under the weight of snow. He said the health situation was "under control."

Nasir said most roads had been cleared, although routes leading to Chakothi on Pakistan's disputed border in Kashmir with India was still blocked, as was another road along the Neelum Valley linking Muzaffarabad with villages on its outskirts.

"Our engineers have cleared almost all main roads after hectic efforts, and aid is being delivered to snow- and rain-hit areas by road," he said.

Kyawoo Maung, an official with the U.N.'s World Food Program, said it and other aid agencies had distributed enough food for 15-30 days, and that there was no risk of starvation for now.