In the Turkish city of Antakya near the Syrian border, where 10-storey buildings had crumbled onto the streets, Reuters journalists saw rescue work being conducted on one out of dozens of mounds of rubble.

The temperature was close to freezing as the rain came down and there was no electricity or fuel in the city.

The magnitude 7.8 quake hit Turkey and neighbouring Syria early on Monday, toppling thousands of buildings including many apartment blocks, wrecking hospitals, and leaving thousands of people injured or homeless.

In Turkey, the death toll climbed to 3,381 people, Turkey's Disaster and Emergency Management Authority (AFAD) said.

The death toll in Syria, already devastated by more than 11 years of war, stands at more than 1,500, according to the Syrian government and a rescue service in the insurgent-held northwest.

Freezing winter weather hampered search efforts through the night. A woman's voice was heard calling for help under a pile of rubble in the southern Turkish province of Hatay. Nearby, the body of a small child lay lifeless.

Weeping in the rain, a resident who gave his name as Deniz wrung his hands in despair.

"They're making noises but nobody is coming," he said. "We're devastated, we're devastated. My God ... They're calling out. They're saying, 'Save us' but we can't save them. How are we going to save them? There has been nobody since the morning."

Families slept in cars lined up in the streets.

Ayla, standing by a pile of rubble where an eight-storey building once stood, said she had driven to Hatay from Gaziantep on Monday in search of her mother. Five or six rescuers from the Istanbul fire department were working in the ruins - a sandwich of concrete and glass.

"There have been no survivors yet. A street dog came and barked at a certain point for long, I feared it was for my mother. But it was someone else," she said.

"I turned on the lights of the car to help the rescue team. They took out only two bodies so far, no survivors.”

In Kahramanmaras, north of Antakya, families gathered around fires and wrapped themselves in blankets to stay warm.

"We barely made it out of the house," said Neset Guler, huddling with his four children. "Our situation is a disaster. We are hungry, we are thirsty. It's miserable."

Ankara declared a "level 4 alarm" that calls for international assistance, but not a state-of-emergency that would lead to mass mobilization of the military.

AFAD official Orhan Tatar said 5,775 buildings had been destroyed in the quake, which had been followed by 285 aftershocks, and that 20,426 people had been injured.

The Turkish disaster agency said 13,740 search and rescue personnel were deployed and more than 41,000 tents, 100,000 beds and 300,000 blankets had been sent to the region.

The earthquake, which was followed by aftershocks, was the biggest recorded worldwide by the U.S. Geological Survey since one in the remote South Atlantic in August 2021.

Another earthquake of 5.6 magnitude struck central Turkey on Tuesday, the European Mediterranean Seismological Centre said.

Monday's quake was the deadliest in Turkey since one of similar magnitude in 1999 that killed more than 17,000. Nearly 16,000 were reported injured in Monday's quake.

Poor internet connections and damaged roads between some of the worst-hit Turkish cities, homes to millions of people, hindered efforts to assess the impact and plan help.

Turkish President Tayyip Erdogan, preparing for a tough election in May, called the quake a historic disaster and said authorities were doing all they could.

In the Turkish city of Iskenderun, rescuers climbed an enormous pile of debris that was once part of a state hospital's intensive care unit in search of survivors. Health workers did what they could to tend to the new rush of injured.

"We have a patient who was taken into surgery but we don't know what happened," said Tulin, a woman in her 30s, standing outside the hospital, wiping away tears and praying.

In Syria, the effects of the quake were compounded by the destruction of more than 11 years of civil war.

In the rebel-held northwest, the death toll stands at more than 740 people, according to the Syrian civil defence, a rescue service known for digging people from the rubble of government air strikes.

The civil defence said hundreds of families were trapped under the rubble and time was running out to save them.

"Every second means saving lives and we call on all humanitarian organisations to give material aid and respond to this catastrophe urgently," said Raed al-Saleh, head of the civil defence.

A top U.N. humanitarian official in Syria said fuel shortages and the harsh weather were creating obstacles to its response.

"The infrastructure is damaged, the roads that we used to use for humanitarian work are damaged, we have to be creative in how to get to the people ... but we are working hard," U.N. resident coordinator El-Mostafa Benlamlih told Reuters in an interview via video link from Damascus.

The death toll in Syrian government-held areas rose to 812, the Syrian state news agency SANA reported. (Reuters)