Aerial footage showing the epicentre of the earthquake
At least 160 people have been killed after an earthquake of 6.4 magnitude hit Balochistan province in south-western Pakistan, officials say.
Officials in Balochistan say they expect the toll to rise.
The tremor struck 70km (45 miles) north of Quetta at 0409 (2309GMT Tuesday) at a depth of 10km (6.2 miles), the US Geological Survey said.
Many houses collapsed during the quake and some were destroyed in landslides that followed it, officials said.
Reports say teams of army and paramilitary Frontier Corps troops are in the area, helping to rescue the injured and retrieve bodies.
Senior army official Maj Gen Salim Nawaz said the area remained accessible for convoys carrying relief material.
But the mountainous region is thinly populated and local infrastructure is poor, making it difficult to get a clear picture of the casualties.
The two main tremors struck at about 0409 and then 0510.
The BBC's Azizullah Khan in Balochistan says aftershocks of 6.2 magnitude have rattled the province on Wednesday, causing more panic among local people.
Officials say there have also been at least four aftershocks.
Our correspondent says communications in many areas have been cut off and many people are scared to return to their homes as another cold night approaches.
Provincial Revenue Minister Zamrak Khan told Reuters news agency that many affected areas had still not yet been reached.
And a local television correspondent reported that some people in villages outside Quetta were angry that no rescue teams had arrived on the scene.
Many stunned survivors spent the rest of the night in the open, with little more than the clothes in which they had been sleeping.
The worst-hit area appeared to be Ziarat, about 50km north of Quetta, where hundreds of mostly mud and timber houses had been destroyed in five villages, mayor Dilawar Kakar said.
Some homes were buried in a landslide triggered by the quake, he said.
"Our rescuers are still working but we've recovered 160 bodies from various villages in Ziarat," he said.
"There is great destruction. Not a single house is intact," he added.
He said hundreds more people had been injured and some 15,000 made homeless.
"I would like to appeal to the whole world for help. We need food, we need medicine. People need warm clothes, blankets because it is cold here," he said.
Another senior official in Ziarat, Sohail-ur-Rehman, said the authorities were also scrambling to bury the dead.
"Graves are being dug with excavators as we can't keep dead bodies in the open," he told the Reuters news agency.
In the village of Sohi, a reporter for AP Television News saw the bodies of 17 people killed in one collapsed house and 12 from another.
Distraught residents were digging a mass grave in which to bury them.
Residents hurried into the streets of Quetta after the quake
"We can't dig separate graves for each of them, as the number of deaths is high and still people are searching in the rubble," village elder Shamsullah Khan said.
In the nearby town of Kawas, dozens of dead and injured were brought to a hospital in Kawas in Ziarat district.
A doctor there, Mohammed Irfan, told the Associated Press news agency the hospital was unable to cope with the number of injured.
Nearby Pishin district was also hit, and at least five people died there.
"We were fast asleep when the tremor struck. We grabbed the children and ran outside. The earth continued shaking for more than a minute," said resident Habibullah.
The quake was also felt in Quetta itself.
"There were two tremors, the second one was serious and people rushed out of their houses," said resident Amjad Hussain.
In 1935, Quetta suffered almost complete destruction in an earthquake which claimed the lives of about 30,000 people.
More than 73,000 people were killed in an earthquake in north-west Pakistan in October 2005 and almost an equal number were seriously injured.