Umm Ibrahim was anxiously waiting for news of her seven children trapped since Monday under the rubble in Syria's second city, after a powerful earthquake that has killed thousands.

Rescuers in Aleppo, Syria's pre-war commercial hub battered by years of conflict, scoured for survivors in the biting winter cold Tuesday as residents buried their dead.

"I haven't been able to eat or drink," said Umm Ibrahim, 56, from the northern city, hit hard by the 7.8-magnitude pre-dawn quake that struck neighbouring Turkey. "How could I, when my children are hungry underground?"

Soldiers, rescuers and residents of Aleppo's Bustan al-Qasr neighbourhood used pickaxes and shovels to free survivors trapped under the debris of collapsed buildings. Umm Ibrahim was among dozens of families who had gathered near a flattened apartment block, searching for loved ones.

She had spent the night sleeping in a car nearby. "I'm waiting for the rescuers to free my children... I will leave it to God," she said, running prayer beads through her fingers.

The region's worst earthquake in over a century has killed more than 6,200 people, at least 1,712 of them in Syria. Aleppo, with at least 290 fatalities, has accounted for more than a quarter of all deaths in government-held areas, Syrian state media said.

More than 50 buildings had been flattened and around 126 shelters were set up in the city. Ancient sites including Aleppo's Old City and its famed citadel were not spared damage. For many of Aleppo's residents, it was a sleepless night. Many spent it in the rough, either in parks or streets, fearing new tremors or because they have lost their home in the quake.

Sitting beside a destroyed building, a young boy in torn flip-flops and two men huddled over a fire to keep warm. Even before the devastating quake, building collapses have been relatively common in the city, mainly due to war damage but also because of shoddy construction.

A former rebel stronghold, Aleppo witnessed brutal battles between rebels and regime forces before it was recaptured by government forces in 2016.

But for some residents, the misery caused by Monday's disaster was like nothing they had seen before.

"This earthquake is more crushing than the war," said Umm Mohammed who has been wandering through the city, desperately searching for her sister, a mother of four -- all of whom are missing. "We looked everywhere, including in hospitals, we couldn't find them." Shops closed along Aleppo's usually bustling streets, as excavators dug up rubble and rescuers yelled for survivors.

Mahmoud Ali was waiting to hear news of relatives still trapped beneath their flattened apartment block. "I heard their phones ring when I called them, then nothing. Their battery must have died," he said, dark circles under his eyes attesting to a sleepless night. "I hope they can hold on until the excavator gets here."

In Aleppo's new cemetery, an AFP correspondent saw men digging graves for quake victims. Ice-cream trucks and minivans transported the bodies, which were then hastily buried, the correspondent said. A family arrived at the cemetery with six dead relatives tucked inside plastic body bags.

They lined them on the ground and recited a prayer before putting them in the ground. Another group came with the bodies of eleven family members. They asked the grave digger to reserve one more spot for a twelfth body -- that of a relative still under the rubble.