The death toll from a strong earthquake in south-eastern Turkey, near Syria’s border, could rise eight-fold, the World Health Organisation has warned.
The toll, which currently stands at more than 3,400 people, has increased rapidly since the first earthquake struck early on Monday morning.
About 12 hours later, a second powerful tremor hit further north.
Rescuers have been combing through mountains of rubble in freezing and snowy conditions to find survivors.
Countries around the world are sending support to help the rescue efforts, including specialist teams, sniffer dogs and equipment.
The US Geological Survey said the 7.8 magnitude tremor struck at 04:17 local time (01:17 GMT) at a depth of 17.9km (11 miles) near the city of Gaziantep.
Seismologists said the first quake was one of the largest ever recorded in Turkey. Survivors said it took two minutes for the shaking to stop.
The second quake – triggered by the first – had a magnitude of 7.5, and its epicentre was in the Elbistan district of Kahramanmaras province.
Many aftershocks are still being felt across the region.
The number of dead and injured from both Turkey and Syria has increased rapidly throughout Monday.
The WHO has warned that those numbers are likely to increase as much as eight times, as rescuers find more victims in the rubble.
“We always see the same thing with earthquakes, unfortunately, which is that the initial reports of the numbers of people who have died or who have been injured will increase quite significantly in the week that follows,” the WHO’s senior emergency officer for Europe, Catherine Smallwood, told AFP.