ISLAMABAD, Pakistan (CNN) -- More than a week into the relief effort after the South Asia earthquake, a U.N. official said Monday the situation remains grave and the effort is facing daunting problems."The race against time is shorter and shorter as weather closes in," said Kevin Kennedy, the United Nations' director for coordination and response for humanitarian affairs.With more than 3.3 million people homeless in and around the Pakistani-controlled region of Kashmir, the threat of hypothermia is increasing as the temperature drops below freezing."We are still at life-saving stage," said Kennedy, who added that 1 million people are severely affected and left "without anything" -- including shelter, medical help and food aid.The United Nations estimates it needs 300,000 tents, saying 20,000 have been delivered, 150,000 are en route and 100,000 more are pledged.The United Nations lists 38,000 dead and 60,000 injured but says it is preparing an update to those numbers.Comparing the earthquake relief efforts with recent disaster responses, Kennedy said it was easier to reach people affected by last year's tsunami because it primarily affected only coastal areas. The South Asia earthquake caused landslides along access routes, making hundreds of thousands of people unreachable by land. The winter temperatures have also made humanitarian aid far more difficult. "Even Hurricane Katrina had better weather," Kennedy said.The United Nations has made an urgent appeal for $312 million. So far, it has received only $6 million with an additional $50 million pledged. "We're only eight days in. The basic message is that we need more resources," Kennedy said.Six die in crashHelicopters resumed relief flights in Pakistan following the crash of an army helicopter early Sunday that killed six people. Torrential rains had caused authorities to temporarily ground planes.The MI-17 transport helicopter was returning home after dropping off relief workers in Bagh when it crashed, killing six Pakistani soldiers.Meanwhile, soldiers worked in the rain to cover up aid supplies delivered by helicopters in previous days. Because of the weather, few relief helicopters took off Sunday.The October 8 quake's epicenter was near Balakot, a city of about 250,000 in Pakistan's North-West Frontier province, 145 kilometers (90 miles) north-northeast of Islamabad.Pakistani Prime Minister Shaukat Aziz's office said Saturday it killed at least 38,000 people in Pakistan and injured 62,000. Another 1,300 deaths were reported in India, most of them in Indian-controlled Kashmir.More than 40,000 Pakistani troops are taking part in rescue and relief efforts, focusing on North-West Frontier province and Pakistani-controlled Kashmir.Officials said 4,000 injured people have been admitted to hospitals in the twin cities of Islamabad and Rawalpindi.Pakistani officials have said as much as 20 percent of the devastated areas have yet to receive any aid due to damaged roads and inclement weather. Pakistani rangers have secured all roads leading to Muzaffarabad, one of the hardest-hit towns, and other affected areas, officials said.Hundreds of rangers are deployed along the routes to stop the looting of trucks carrying relief supplies to the most affected areas, said a rangers official.Roads to many areas were clogged with traffic, slowing ground efforts to reach the most vulnerable.Meanwhile, Saudi King Abdullah II donated $133 million for victims of the quake, said Ali Asseri, Saudi Arabia's ambassador in Pakistan.The money will be used to construct schools, hospitals and roads in the region, and will be available to the Pakistani government immediately, Asseri told CNN.The king has also ordered the dispatch of a daily fleet of 10 cargo planes filled with relief supplies to Pakistan until the country's need for goods, medicines, tents and food for victims is fulfilled.Aziz said Saturday the quake had caused an estimated loss of $5 billion in his country.The quake has prompted rival nations to put aside their differences -- at least for the moment -- to help the tens of thousands of people left homeless. India, which has fought three wars with Pakistan since 1947, sent a plane loaded with humanitarian supplies on Friday to Lahore. It was the second shipment to its nuclear rival.When an Iranian plane arrived at Chaklala air base in Pakistan, it received help with unloading the cargo from U.S. military personnel already on site. (Watch efforts to get aid to hard-hit areas -- 2:40)The quake, however, has not ceased violence in the region. Militants in Indian-controlled Kashmir killed two Indian army soldiers and wounded six others early Saturday at an Indian army camp in the town of Kathua, according to state police sources.CNN's Becky Anderson, Satinder Bindra, Ram Ramgopal and Syed Mohsin Naqvi contributed to this report.