So far, nearly 200 people have been reported killed in the earthquakes that hit southeastern Turkey and northern Syria on the night of Monday. The death toll is expected to rise.

Dozens of buildings have collapsed in both Turkey and Syria and many are feared to have died in the tremors.

Turkey's rescue agency says at least 76 people have been confirmed dead in seven Turkish provinces. According to the authority, at least 440 people have been injured.

In Syria, state media reports at least 111 deaths in government-controlled parts of the country. At least 20 people are said to have died in the rebel-held region of northwestern Syria.

USGS estimate: Up to 1,000 may have died

According to the United States Geological Survey USGS, as many as 1,000 people may have died in the quake. The calculation is made based on the earthquake's magnitude, at what depth they occurred and the conditions in the earthquake area, for example the safety of buildings.

In northwestern Syria, the opposition civil defense describes the situation as catastrophic with many buildings having collapsed and people trapped under the rubble.

The first quake had a magnitude of 7.8 and occurred at a depth of 17.9 kilometers at 4:17 a.m. local time, according to the USGS.

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The epicenter was about 33 kilometers from the provincial capital Gaziantep and 26 kilometers from the city of Nurdagi, located in the southeastern part of the country.

The second quake, with a magnitude of 6.7, occurred at 04:28 at a depth of 9.9 kilometers.