The quake in the province of Balochistan had a relatively shallow depth of about 9 km (6 miles), according to the U.S. Geological Survey (USGS). Shallower quakes tend to cause more damage.
Its epicenter was about 100 km (62 miles) east of the provincial capital Quetta, and about 14 kilometers (8 miles) north-northeast of Harnai.
Rescue workers said those who died were mostly women and children, reported Reuters.
The quake had struck while people were sleeping, just past 3 a.m. local time.
More than 100 mud houses collapsed while a large number of other buildings, including government buildings, were damaged. At least one coal mine collapsed amid the quake.
Sohail Anwar, deputy commissioner in the city of Harnai, told Reuters that hundreds of people were rendered homeless.
Residents gathered outside in the dark following the quake. More than 200 people were injured and were rushed to hospital, or treated on stretchers in the street under light provided by mobile phones.
Relatives crowded outside the District Headquarter Hospital Harnai. Manzoor Ahmed, a medical superintendent at the hospital, told The Associated Press, “So far we’ve managed more than 200 casualties, we have received 15 dead bodies.
“We sent some severely injured by road, using ambulances and private vehicles, to Quetta for better treatment,” he added. “Those who are in serious condition, we are shifting them using helicopters.”
Provincial minister Zia Langove told Al Jazeera that rescue workers faced blocked roads in the area due to landslides caused by the earthquake. He said teams were working to clear roads to the affected areas and will assess the damage further.
Officials said the death toll was expected to rise.
A 7.7-magnitude earthquake hit Quetta in 1935. It killed between 30,000 to 60,000 people.
Reuters and The Associated Press contributed to this report.