Baluchistan province in southwest Pakistan where the tremor hit is the country's largest but also the least populated. The quake appears to have been centered in one of its more remote areas.
At least two people were killed and five others were injured when more than two dozen houses collapsed in villages of Awaran district where the quake struck, said the district's deputy commissioner Abdur Rasheed. He said rescue teams have been dispatched to the area.
The magnitude 7.7 quake hit in the southern part of the province, said Pakistan's chief meteorologist, Mohammed Riaz. The U.S. Geological Survey in Golden, Colo. reported the quake as magnitude 7.8.
The quake struck in a remote area of Baluchistan with little population, said the head of Pakistan's Earthquake Center, Zahid Rafi. He warned of possible aftershocks.
In the town of Awaran, roughly 50 kilometers (30 miles) south of the epicenter, Khair Mohammed Baluch said his family rushed outside when the quake struck.
"We all ran out for safety in the open field in front of our house. Many other neighbors were also there. Thank God no one was hurt in our area but the walls of four or five house collapsed," he said.
The area where the quake struck is at the center of an insurgency that Baluch separatists have been waging against the Pakistani government for years. The separatists regularly attack Pakistani troops trying to suppress the uprising as well as symbols of the Pakistani state, such as infrastructure projects.
The quake was felt as far away as New Delhi, the Indian capital, but no damage or casualties were immediately reported, said Jai Chandra, a meteorologist with the India Meteorological Department.
The quake was also felt in Pakistan's largest city, Karachi, along the Arabian Sea, roughly 250 kilometers (155 miles) from the epicenter. People in the city's tall office buildings rushed into the streets following the tremor, and Pakistani television showed images of lights swaying as the earth moved.
"I was working on my computer in the office. Suddenly I felt tremors. My table and computer started shaking. I thought I am feeling dizziness but soon realized they were tremors," said one Karachi resident, Mohammad Taimur.
A security guard at a bank in one of the buildings said he locked the doors after everyone left the office and then rushed into the street.
"At the time I felt the strong shock, I went inside the office to watch the TV. Other people were yelling 'Earthquake! Leave the office!" said Muhammad Akhtar.
In Quetta, the capital of Baluchistan, people also fled their homes and offices in panic.
Matiullah Khan, a cell phone vendor in Quetta, said he was in his shop handling a customer when the cabinet and shelves started to shake.
"I along with customers rushed out to the main street ... Thousands of people were standing, many in fear and reciting Quranic verses," he said, referring to Islam's holy book, the Quran.
Baluchistan and neighboring Iran are prone to earthquakes.
A magnitude 7.8, which was centered just across the border in Iran, killed at least 35 people in Pakistan last April.
In January 2011, a 7.2 magnitude quake damaged 200 mud-brick homes in a remote area of Baluchistan about 200 miles (320 kilometers) southwest of Quetta not far from the Afghan border, but caused no casualties.