Syria’s war-torn city of Aleppo is one of the places to have borne the brunt of the deadly earthquake, which also devastated parts of southern Turkey.
More than 1,600 people have been reported dead so far in northern Syria following the quake.
Emergency rescue teams said many buildings were damaged or destroyed and that people were trapped under the rubble.
The region is home to millions of refugees displaced by the civil war.
Control of northern Syria is divided between the government, Kurdish-led forces and other rebel groups. They remain embroiled in conflict.
Even before the earthquake the situation in much of the region was critical, with freezing weather, crumbling infrastructure and a cholera outbreak causing misery for many of those who live there.
Much of Aleppo was destroyed in the civil war, which broke out in 2011 when a peaceful uprising against President Bashar al-Assad turned into violence.
While there have been efforts to rebuild the city – Syria’s pre-war commercial hub – there is dilapidated infrastructure, plus destroyed buildings, and power outages are common.
According to separate figures from the Syrian government and the White Helmets rescue group, which operates in rebel-controlled areas, more than 1,600 people have died in the region so far after the earthquake.
A video published on social media, and verified by the BBC, showed a building in Aleppo crashing to the ground as onlookers rushed to safety.
The 7.8 magnitude earthquake struck at 04:17 local time (01:17 GMT) at a depth of 17.9km (11 miles) near the Turkish city of Gaziantep. Twelve hours later, a second quake, which was nearly as large, struck 130km (80 miles) to the north.
Some Aleppo residents told correspondents they have nowhere to go, either because their homes have been destroyed or because they are afraid of further quakes.