At least 592 people were killed in Syria as buildings collapsed after a 7.8 magnitude earthquake struck neighbouring Turkey before dawn on Monday, state media and rescuers said.
AFP correspondents in northern Syria said terrified residents ran from their homes after the earthquake hit near the Turkish city of Gaziantep, about 40 kilometres (25 miles) from the Syrian border.
Rescuers rushed to dig for survivors under the rubble of collapsed buildings in the pouring winter rain.
The quake killed at least 371 people and left at least another 1,089 injured in government-controlled parts of Syria, including the cities of Aleppo, Hama, Latakia and Tartus, the official news agency SANA reported, citing the health ministry.
In rebel-held parts of the northwest of the country, at least 221 people were killed and at least another 419 were injured, rescue workers said.
The White Helmets rescue group, which operates in rebel-controlled areas of the war-torn country, said on Twitter that the number was "expected to rise as hundreds of families (are) still trapped".
The group said its teams were facing "difficulty" as hundreds of people were stuck under rubble, adding that heavy equipment was needed.
SANA said the earthquake was felt from Latakia on the coast in the west to Damascus.
"This earthquake is the strongest since the National Earthquake Centre was founded in 1995," Raed Ahmed, who heads the centre, told SANA.
Near the border town of Azaz, an AFP correspondent saw rescuers pull survivors as well as five bodies from the rubble of a three-storey building that had collapsed.
Deaths were also reported in northern Syrian areas controlled by pro-Turkish factions.
"We have been working on rescuing survivors and recovering the dead from under the rubble" in the regions of Azaz and Al-Bab, Omar Alwan, the medical response coordinator for the area, told AFP.
Dozens of rescuers and residents had toiled in the darkness, using flashlights to look for survivors in the rubble.
In Azmarin on the Turkish border, at least 10 buildings had collapsed, an AFP correspondent in the town reported.
The earthquake hit near Gaziantep in southeastern Turkey at 04:17 am (0117 GMT) at a depth of about 17.9 kilometres (11 miles), the US Geological Survey said.
Tremors were also felt in Lebanon and Cyprus, AFP correspondents said.