ADANA, Turkey (AP) — A powerful 7.8 magnitude earthquake rocked wide swaths of Turkey and neighbouring Syria on Monday killing more than 2,500 people and injuring thousands more as it toppled thousands of buildings and trapped residents under mounds of rubble.

Authorities feared the death toll would keep climbing as rescuers searched through tangles of metal and concrete for survivors in a region beset by more than a decade of Syria's civil war and a refugee crisis.

Residents jolted out of sleep by the pre-dawn quake rushed outside in the rain and snow to escape falling debris, while those who were trapped cried for help.

Throughout the day, major aftershocks rattled the region, including a jolt nearly as strong as the initial quake. After night fell, workers were still sawing away slabs and still pulling out bodies as desperate families waited for news on trapped loved ones.

"My grandson is 1 1/2 years old. Please help them, please. We can't hear them or get any news from them since morning. Please, they were on the 12th floor," Imran Bahur wept by her destroyed apartment building in the Turkish city of Adana. Her daughter and family were still not found.

Tens of thousands who were left homeless in Turkey and Syria faced a night in the cold.

In Turkey's Gaziantep, a provincial capital about 33 kilometres (20 miles) from the epicentre, people took refuge in shopping malls, stadiums and community centres. Mosques around the region were opened to provide shelter.

The quake, which was centred on Turkey's south-eastern province of Kahramanmaras, sent residents of Damascus and Beirut rushing into the street and was felt as far away as Cairo.

Turkish Vice-President Fuat Oktay said such a disaster could hit "once in a hundred years". Turkish President Recep Tayyip Erdogan said official do not know how high the number of dead and injured will rise.