More than 3,500 people have died after a huge earthquake hit Turkey and Syria.
The 7.8-magnitude quake was centred in the town of Pazarcik in Kahramanmaras province, about 20 miles from the city of Gaziantep, at a depth of six miles and there were several powerful aftershocks.
With thousands injured, the death toll is expected to increase as rescue workers search the rubble.
Another 7.5 magnitude earthquake later hit central Turkey.
On both sides of the border, residents were jolted from their sleep and rushed outside on a cold, rainy and snowy winter night as buildings fell around them and strong aftershocks continued.
"I have never felt anything like it in the 40 years I've lived," said Erdem, a resident of Gaziantep. "We were shaken at least three times very strongly, like a baby in a crib."
The quake heavily damaged Gaziantep's most famous landmark, a historic castle perched atop a hill in the centre of the city. Parts of the fortresses' walls and watch towers collapsed, with other parts heavily damaged, images showed.
At least 20 aftershocks followed the quake, the strongest measuring 6.6, according to Turkish authorities.
Rescue workers and residents worked through tangles of metal and giant piles of debris in their search for survivors.
Turkish broadcaster RTR showed rescue workers in Osmaniye province using a blanket to carry an injured man from a collapsed four-storey building - he was the fifth to be pulled from the rubble, it said.
'Level 4 alarm' raised
Turkish President Recep Tayyip Erdogan said it was unclear how high the number of dead and injured could rise to.
"Because the debris removal efforts are continuing in many buildings in the earthquake zone, we do not know how high the number of dead and injured will rise," Mr Erdogan said.
"Hopefully, we will leave these disastrous days behind us in unity and solidarity as a country and a nation."
He said 2,818 buildings collapsed after the first tremor, describing it as the country's "largest disaster" since 1939, when a major earthquake struck the eastern province of Erzincan.
Turkish Vice President Fuat Oktay declared a "level 4 alarm" that calls for international assistance.
'We are under extreme pressure' as teams work in rain and sleet
In Syria, already devastated by more than 11 years of civil war, numerous buildings tumbled down in the provinces of Hama, Aleppo and Latakia and the central city of Hama.
State TV showed footage of rescue teams searching for survivors in heavy rain and sleet.
In the northwest of the country, the opposition's Syrian Civil Defence described the situation in the rebel-held region as "disastrous", adding that entire buildings have collapsed and people are trapped under the rubble.