According to international media, the quake, which hit in the early darkness of a winter morning, was also felt in Cyprus and Lebanon.
“I have never felt anything like it in the 40 years I’ve lived,” said Erdem, a resident of the Turkish city of Gaziantep, near the quake’s epicentre, who declined to give his surname.
Turkey’s disaster agency said 913 people had been killed, as authorities scrambled rescue teams and supply aircraft to the affected area, while declaring a “level 4 alarm” that calls for international assistance.
Syrian state media said more than 386 people were killed there, most in the provinces of Hama, Aleppo and Latakia, where numerous buildings had been brought down.
Many buildings in the region had already suffered damage in fighting during Syria’s nearly 12-year-long civil war.
People in Damascus, and in the Lebanese cities of Beirut and Tripoli, ran into the street and took to their cars to get away from their buildings in case they collapsed, witnesses said.
In Turkey’s Gaziantep, Erdem also said people had fled from their shaking homes and were too scared to return.
“Everybody is sitting in their cars or trying to drive to open spaces away from buildings,” Erdem said by telephone.
The United States was “profoundly concerned” about the quake in Turkey and Syria and was monitoring events closely, White House national security adviser Jake Sullivan said on Twitter.
The region straddles seismic fault lines and is prone to earthquakes.