The five deaths were recorded in the remote Kharan district of Balochistan, state-run Radio Pakistan reported.
TV news channels quoted security officials as saying that three children and two women were killed when several buildings collapsed in Mashkel area of Kharan.
The dead and injured were taken to a hospital run by security forces, officials said.
The high-intensity earthquake measuring 7.9 on the Richter scale rattled several parts of Pakistan, including Karachi, Hyderabad and Quetta cities.
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Hundreds of people had rushed out of their offices and homes in panic in the Pakistan's biggest city and in cities across the Sindh and Baluchistan provinces as soon as the jolts were felt around 3.46 pm local time that lasted for around 15 seconds.
"I felt the whole building shaking. It was very scary. There were one or two powerful jolts," Abbas, an employee of the Geo news channel, said as he rushed out of the building.
There were no reports of casualties from other areas.
The epicentre of the quake was in Iran, where state-run Press TV reported at least 40 people had died.