UPDATE 2: Earthquake measuring 6.4 on Richter scale hits close to city of Quetta, many left homeless.
A powerful earthquake struck southwest Pakistan before dawn on Wednesday, killing at least 160 people, destroying mud homes and sending survivors screaming into the streets in panic.
At least eight villages were badly hit by the 6.4-magnitude quake, local police and officials said, warning the death toll could rise as rescue workers reached villages in the remote mountainous region bordering Afghanistan.
"Around 160 people have died so far," said Khushal Khan, spokesman for the revenue minister of gas-rich Baluchistan province, Zamarak Khan.
"The toll may go up. The dead included 29 members of the same family."
Residents in the region around the historic hill town of Ziarat, about 50 kilometres (30 miles) north of the provincial capital Quetta, told him about 6,000 people have been made homeless, he said.
President Asif Ali Zardari and Prime Minister Yousuf Raza Gilani both expressed their condolences to relatives of those killed and injured and called for a country-wide response, the state-run Associated Press of Pakistan said.
The first official government figures from the National Disaster Management Authority (NDMA) put the death toll at 115 so far, with nearly 300 injured, its chairman, retired Lieutenant General Farooq Ahmed, told a news conference.
In Quetta, witnesses said people fled screaming from their homes. Television footage showed many outside in the streets, wrapped up against the early morning chill.
But most of the victims were from outlying villages, whose mud houses were destroyed by the tremors, which triggered landslides of rocks and boulders while people slept in their beds.
In the village of Wam, near Ziarat, survivors later began burying their dead in line with Islamic tradition. At least 75 bodies were removed from the rubble, a local charity, Edhi, said.
Others desperately dug among the rubble of demolished houses in the hope of finding loved ones alive or their bodies, an AFP correspondent witnessed.
Mohammed Sultan, from the town of Sanjawai, told AFP the first tremor shook him awake shortly before 5:00 am, before he felt a larger shockwave about 10 minutes later.
In Ziarat buildings had collapsed and communications had been cut, he said, adding: "The town looks devastated. Parts of it are badly damaged. My relatives live in Ziarat but I can't contact them to find out how they are."
The Quetta to Ziarat road was also hit, with wide cracks in places and boulders from landslides, an AFP correspondent said.
The US Geological Survey said the quake struck at 3am Dubai time. Its epicentre was located some 70 kilometres north of Quetta, about 185 kilometres southeast of the Afghan city of Kandahar, they added.
Soldiers, helicopters, tents, blankets, food and medical help have been sent from Quetta to Ziarat and an aerial assessment of the damage has started, the Pakistani military said.
"The destruction is heavy, people need immediate help and we are providing assistance to the affected people," Colonel Mohammed Babar, who flew over the region, told AFP.
The NDMA's Ahmed said there had been 12 after-shocks and more were expected over the coming days.
Over the border in Afghanistan, there were no immediate reports of casualties or structural damage in Kandahar, police there said.
Ziarat is a historic hill resort famed for its juniper forests. It receives visitors from all over Pakistan in summer who come to see the holiday home of the country's founder, Mohammed Ali Jinnah.
Most of the casualties were from two villages built on steep ground on the outskirts of the town.
A 7.6-magnitude earthquake in northwest Pakistan and Kashmir killed 74,000 people and displaced 3.5 million in October 2005.
In 1935 a massive quake killed around 30,000 people in Quetta, which at the time was part of British-ruled India.