At least 23 people were killed and more than 200 injured in an earthquake in southern Pakistan. The 5.9 magnitude earthquake struck in the early hours of Thursday, while people were sleeping. The US Geological Survey said the quake occurred at a depth of nine kilometres, with the epicentre near Harnai in Balochistan province, about 100 kilometres east of the provincial capital Quetta. The agency initially reported the strength of the tremor as 5.7 before revising it to 5.9. Most of the local population in the remote mountainous region live in mud houses, many of which collapsed. Other homes and government buildings suffered damage. Rescue workers said the dead were mostly women and children. They include a mother who died with her two young sons when their home collapsed, and an eight-year old girl who lived near by whose body was found beneath the rubble of her home. Rafiullah, a farmer, said he was knocked unconscious when the roof of his home collapsed. "When I regained consciousness, I pulled out two of my sons," he told AFP. But his youngest boy, about a year old, had been struck by a wooden beam and was already dead, he said. Suhail Anwar Shaheen, deputy commissioner of the area, said at least four people were killed when one of the many coal mines in the area collapsed. Mr Shaheen said the death toll was expected to rise as rescuers continued their search. Prime Minister Imran Khan said he had ordered emergency assistance to the area and promised compensation to those affected by the earthquake. "I have ordered immediate assistance on an emergency basis for the Harnai, Balochistan, earthquake victims and for an immediate assessment of the damage for timely relief and compensation. My condolences and prayers go to the families who lost their loved ones," Mr Khan wrote on Twitter. Pakistan’s military said it airlifted dozens of injured from mountain peaks and sent search and rescue teams to the area. At least nine critically injured people were taken to the provincial hospital in Quetta. Hundreds of people were left homeless by the earthquake, Sohail Anwar, deputy commissioner in Harnai, told Reuters. Videos on social media showed houses shaking and light fittings swaying as the quake struck and, later, stunned residents gathering in the dark. “Women, children, everyone was running here and there,” Ghulam Khan, a villager, told Associated Press. “We were scared and we didn’t know what to do.” Many of the injured were taken to the district hospital in Harnai, where doctors treated them outside on the street as tremors continued to shake the area. “So far we have treated more than 200 casualties,” said Manzoor Ahmed, medical superintendent of the hospital. The small rural facility has been taxed to the limit, he said. As many as 15 bodies were taken there. By early afternoon, funerals were being held in the small villages dotting the mountains. A 7.7 magnitude earthquake hit Quetta in 1935, killing as many as 60,000 people, making it one of the deadliest quakes to hit South Asia.