KAHRAMANMARAS/ANTAKYA: The official death toll of a devastating earthquake in Turkey and Syria jumped to more than 8,700 people on Wednesday as overwhelmed rescuers warned that the number would grow significantly with families still trapped under the rubble.

In Turkey, many people spent a second night of freezing temperatures sleeping in their cars or in the streets under blankets, worried to go back into buildings shaken by Monday's 7.8 magnitude quake - the country's deadliest since 1999.

"Where are the tents, where are food trucks?" said Melek, 64, in the southern city of Antakya, adding that she had not seen any rescue teams.

"We haven't seen any food distribution here unlike previous disasters in our country. We survived the earthquake, but we will die here due to hunger or cold here."

With the scale of the disaster becoming ever more apparent, the death toll - now 6,234 in Turkey - looks likely to keep on rising.

In neighbouring Syria, already devastated by 11 years of war, the death toll climbed to more than 2,500 overnight, according to the Syrian government and a rescue service operating in the rebel-held northwest.

Turkish President Tayyip Erdogan has declared a state of emergency in 10 provinces. But residents in several damaged Turkish cities have voiced anger and despair at what they said was a slow and inadequate response by the authorities.

The initial quake struck just after 4 a.m. on Monday, the dead of night in the dead of winter, giving the sleeping population little chance to react.

Erdogan, facing a tight election in May, is expected to visit some of the affected areas on Wednesday.

Turkish authorities say some 13.5 million people were affected in an area spanning roughly 450 km (280 miles) from Adana in the west to Diyarbakir in the east - broader than that between Boston and Philadelphia, or Amsterdam and Paris.

'UNDER THE RUBBLE'

The quake, followed hours later by a second one almost as powerful, toppled thousands of buildings including hospitals, schools and apartment blocks, injured tens of thousands, and left countless people homeless in Turkey and northern Syria.

Rescue workers have struggled to reach some of the worst-hit areas, held back by destroyed roads, poor weather and a lack of resources and heavy equipment. Some areas are without fuel and electricity.

Aid officials voiced particular concern about the situation in Syria, where humanitarian needs were already greater than at any point since the eruption of a conflict that has partitioned the nation and is complicating relief efforts.

The head of the World Health Organization has said the rescue efforts face a race against time, with the chances of finding survivors alive slipping away with every minute and hour.

In Syria, a rescue service operating in the insurgent-held northwest said the number of dead had climbed to more than 1,280 and more than 2,600 were injured.

"The number is expected to rise significantly due to the presence of hundreds of families under the rubble, more than 50 hours after the earthquake," the rescue service said on Twitter.

Overnight, the Syrian health minister said the number of dead in government-held areas rose to 1,250, the state-run al-Ikhbariya news outlet reported on its Telegram feed. The number of wounded was 2,054, he said.

Turkey's deadliest earthquake in a generation has handed Erdogan a huge rescue and reconstruction challenge, which will overshadow the run-up to the May elections already set to be the toughest of his two decades in power.

The vote, too-close-to-call according to polls before the quake, will determine how Turkey is governed, where its economy is headed and what role the regional power and NATO member may play to ease conflict in Ukraine and the Middle East.