The US Geological Survey on its website said a magnitude 6.4 earthquake struck 60 kilometres north-east of Quetta, the capital of Balochistan at 5:10 am (2310 GMT).
People fled their houses in panic as the shocks hit Balochistan just before sunrise, while television footage showed terrified families wrapped in blankets sitting by the roadsides in Quetta.
Ziarat, located around 50 kilometres from Quetta, was the most severely affected district.
More than 80 people have been killed in Wam village where hundreds of houses were damaged, a senior official in Ziarat, Sohailur Rehman, told DawnNews television channel.
Rehman was overseeing the rescue efforts in the village.
There were reports of more death in Ziarat as well as other areas of the province, including Pishin and Khoshab, where five people died and dozens more were injured.
However, provincial head of the paramilitary Frontier Corps (FC), Major General Asif Nawaz, confirmed 30 deaths.
But he feared that the death toll might rise as many people are believed to be trapped under demolished houses. Nawaz said the FC troops had been dispatched to the areas for relief operations.
The officials were trying to assess the extent of the destruction by the earthquake in Balochistan, which is Pakistan's largest but most sparsely populated province.
The relief workers have so far reached only those villages that are located close to main roads while many remote areas still remain inaccessible
The earthquake also triggered mudslides in several hilly areas, blocking the roads and hampering the relief work. Military helicopters were flown to the area.
A massive earthquake measuring 7.6 on the Richter scale shook Kashmir and Pakistan's mountain region on October 8, 2005, killing at least 73,000 people and rendering more than 3.5 million others. dpa ns yam fi ff pw
- Deutsche Presse Agentur
- Copyright (c) dpa Deutsche Presse-Agentur GmbH