At least 20 people were killed and more than 200 injured when an earthquake struck different parts of Balochistan, National Disaster Management Authority (NDMA) Director General Naseer Nasir said on Thursday.

The earthquake with a magnitude of 5.9 struck in the early hours of Thursday while people were sleeping. Rescue workers said the dead were mostly women and children.

The quake was relatively shallow at 20 kms (12 miles) with an epicentre 102 km (62 miles) east of Quetta, said the US Geological Survey (USGS).

Along with other areas of the province, the disaster hit Harnai district, while the earthquake tremors were also felt in Quetta, Sibi, Mastung, Shahrag and other adjoining areas.

More than 100 mud houses collapsed and a large number were damaged, including government buildings. Hundreds of people were rendered homeless, Sohail Anwar, deputy commissioner in the city of Harnai, told Reuters.

The bodies of 10 people, including six children, and over 150 wounded people have been shifted to the hospital, according the MS Harnai Hospital, reported Geo News.

Social media showed houses shaking and light fittings swaying as the quake struck, and later stunned residents gathering in the street in the dark.

Rescue and relief operation

The injured were rushed to hospital, while some were treated on stretchers in the street under phone torch light.

In a tweet, the NDMA spokesperson shared pictures of rescue operation in earthquake-hit areas and said: "Rescue & Relief operation is underway after devastating Earthquake in Balochistan. Army's special Rescue & Relief team being airlifted to Quetta & Hurnai."

Balochistan Home Minister Ziaullah Langove told media that PDMA Balochistan had dispatched rescue teams to Harnai and other affected districts.

According to the home minister, the PDMA has sent heavy machinery and rescue teams to the affected areas from Quetta, read the Geo report.

He said that there were reports of damage in Ziarat, Qila Saifullah and Sibi while most of the casualties were reported in Harnai. Many people are still stuck under the rubble of collapsed buildings, he added.

Langove said there are reports of damage coming Ziarat, Qila Saifullah and Sibi also. "We will not leave people without help. We will make up for the losses," he said.

An emergency was also enforced in Quetta hospitals, he said.

Social media users shared pictures of disaster in the province and rescue operation.

Expressing grief over the loss of lives in earthquake, leader of opposition in the National Assembly Shehbaz Sharif tweeted: "Sad over the loss of precious lives due to earthquake in Balochistan last night."

A 7.7-magnitude earthquake hit Quetta in 1935, killing between 30,000 and 60,000 people, making it one of the deadliest quakes to hit South Asia in recorded history.