At least 53 people were killed in Turkey and 42 people died in neighbouring Syria after a major earthquake measuring 7.8 on Richter scale hit southeastern Turkey on Monday, according to the United States Geological Survey (USGS).

With the earthquake flattening buildings across many cities, the toll is likely to go up as rescue operations are on amid the debris.

The quake struck 23 kilometers  east of Nurdagi in Turkey located along the Syria border and the quake was felt in several countries across the region.

According to a CNN report, the quake struck while residents were likely asleep and unprepared for the impact. Video shared on social media show dozens of collapsed buildings, while frightened residents huddled on the darkened streets amid the chaos. Rescue workers can be seen conducting search-and-rescue operations by flashlight.

The governor of Sanliurfa province, Salih Ayhan, told CNN affiliate CNN Turk that at least 12 people have died in his province alone. At least 34 buildings had collapsed, according to preliminary data, Erdinç Yılmaz, governor of the southern Osmaniye province said.

Strong aftershocks have been felt in southern and central Turkey. About 11 minutes after the main quake hit, the strongest aftershock of 6.7-magnitude hit about 32 kilometers (20 miles) northwest of the main quake’s epicentre. Another intense aftershock with a magnitude of 5.6 then occurred 19 minutes after the main quake.