A major earthquake with a magnitude of 7.2 has hit southwest Pakistan, the US Geological Survey says.
The quake was centred near the border with Afghanistan, about 34 miles west of Dalbandin, a town in a sparsely-populated area of Baluchistan province.
It struck at about 1.20am local time (8.20pm GMT) and caused widespread panic as it was felt throughout several provinces, according to local TV reports.
In Karachi, there are reports that tremors caused buildings to shake.
Tremors lasting at least 20 seconds were felt as far away as Dubai in the United Arab Emirates and in India's capital, New Delhi.
The quake was also felt by British troops in Camp Bastion, Afghanistan, where the UK Forces media team described the tremors as "very noticeable".
A member of the team wrote on Twitter: "Felt like a ship moving on a choppy sea."
There have been no immediate reports of damage or casualties.
The exact epicenter was in a remote area some 200 miles southwest of the Baluchistan capital of Quetta and about the same distance from the Iranian city of Zahedan, both home to hundreds of thousands of people.
Quakes often rattle the region. In 2005, one measuring 7.6 on the Richter scale killed about 80,000 people in northwestern Pakistan and Kashmir and left more than three million homeless.
The Iranian city of Bam, which lies west of Zahedan, was hit by a severe earthquake in 2003.