The worst-hit area appeared to be Ziarat, 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.
"There is great destruction. Not a single house is intact," Kakar told Express News television.
Maulana Abdul Samad, the minister for forests in Baluchistan, said at least 150 people were confirmed to have died. Kakar said hundreds of people have been injured and some 15,000 were 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," Kakar said.
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.
"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" of many other homes, said Shamsullah Khan, a village elder.
Other survivors sat stunned in the open, with little more than the clothes in which they had been sleeping.
Hospitals in the nearby town of Kawas and the provincial capital Quetta were flooded with the dead and injured.
One patient in Quetta Civil Hospital, Raz Mohammed, said he was awoken by the sound of his children crying before he felt a jolt.
"I rushed toward them but the roof of my own room collapsed and the main iron support hit me," he said. "That thing broke my back and I am in severe pain but thank God my children and relatives are safe."
With some roads blocked by landslides, officials said the army was ferrying hundreds of troops and medical teams on four helicopters to villages in the quake zone and had set up a field hospital in Quetta.
Officials said they were distributing thousands of tents, blankets and food packages and sending in earth-moving equipment to help dig mass graves.
The quake struck two hours before dawn and had a magnitude of 6.4, the U.S. Geological Survey reported. It was a shallow 10 miles below the surface and was centered about 400 miles southwest of the capital, Islamabad.
Pakistan is prone to violent seismic upheavals. Wednesday's quake was the deadliest since a magnitude-7.6 quake devastated Kashmir and northern Pakistan in October 2005, killing about 80,000 people and leaving hundreds of thousands homeless.
Officials said the area hit on Wednesday was much less densely populated.
Baluchistan is home to a long-running separatist movement, but is not considered a major battleground in the fight against Taliban insurgents that plague other border regions.
Associated Press writer Mattiullah Achakzai in Quetta and APTN cameraman Abdul Rahman in Sohi contributed to this report.