Aid has begun to reach remote regions near the epicentre of Saturday's devastating earthquake in Nepal.
As relief efforts continue in the Kathmandu Valley, the UN says the response is broadening to include hard hit areas such as Dhading and Gorkha.
The 7.8-magnitude quake killed more than 5,000 people. Many survivors are in desperate need of food and water.
Thousands of people are queuing to board buses and leave the capital, amid fears of further aftershocks.
"We are scared of the epidemics that may spread because of all those dead bodies," a man waiting at Kathmandu's main bus station told the BBC. "Just to be safe, I'm leaving town for a while."
Early on Wednesday police at the station scuffled with people trying to get on to crowded buses.
In other developments:
- The UN has launched an appeal for $415m (£270m) to provide emergency relief over the next three months
- Nepalese officials have denied reports from some international charities that Western tourists were given priority during evacuations from around Mount Everest
- About 210 foreign trekkers who were stranded in Langtang, north of Kathmandu, are reported to have been airlifted to the nearby town of Dhunche
At the scene: Sanjoy Majumder, BBC News, Kathmandu
There's a rush to get out of Kathmandu. Thousands of people are trying to flee - some trying to head out to the remote districts to see how their families are, others including tourists trying to head towards India by road.
But there simply aren't enough buses to take them out and the highways are choked with vehicles, people and relief convoys. Tempers are flaring. The police came to the bus station to restrain those trying to board crowded buses, which made it worse.
Outside Kathmandu airport, there are lines of tourists trying their best to get a ticket to fly home. The airlines have laid on extra flights but it's not enough and also, the airport is finding it hard to cope with the additional rush as well as the influx of cargo aircraft bringing in relief material.
Rescue operations resumed on Wednesday following bad weather.
Bella Messenger, an NGO worker in an isolated area of Gorkha district, told the BBC that Chinese lorries had brought aid to the area, but many people remained cut off.
"You can't get to some villages without a helicopter," she said.
There was some good news when a man trapped in the rubble of a Kathmandu hotel for 82 hours was pulled to safety by Nepalese and French teams.
Rishi Khanal, 27, said he had been surrounded by dead bodies and drank his own urine to survive.
"I had some hope but by yesterday I'd given up. I was sure no-one was coming for me. I was certain I was going to die," he told AP news agency from his hospital bed.
Areas worst affected
More than eight million people have been affected by the quake, the UN says. About 10,000 people have been injured.
Hundreds of thousands of people continue to live in temporary camps, in squalid conditions with very little food and water, says the BBC's Sanjoy Majumder in Kathmandu.
Officials admit they have been overwhelmed by the scale of the disaster, but highlight the challenges it poses in one of Asia's poorest countries.
"The government is trying its best to deliver the relief materials," National Disaster Management chief Rameshwor Dangal told the BBC. "The problem is the level of disaster is very high and it's spread over more than 20 districts."
Renaud Meyer of the UN Development Programme said Kathmandu's single-runway airport was struggling to accommodate the rush of aid flights, but teams were delivering supplies as quickly as possible.
On Mount Everest - where the quake triggered an avalanche that killed at least 18 people - all stranded climbers have now been evacuated from base camp.
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