The screams of people still trapped in the rubble filled the night early on Tuesday and relatives wept for their loved ones as the death toll in Turkey and in neighbouring northwest Syria rose to more than 3,700, Reuters reports.
The magnitude 7.8 quake rippled through both countries early on Monday, toppling entire apartment blocks, wrecking hospitals, and leaving thousands more people injured or homeless.
Freezing winter weather hampered search efforts for survivors through the night into Tuesday.
Under a pile of rubble in the southern province of Hatay, a woman's voice could be heard calling for help. Nearby, the body of a small child lay lifeless.
Weeping in the rain, a local 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."
Temperatures fell close to freezing overnight, worsening conditions for people trapped under rubble or left homeless.
In Kahramanmaras, north of Hatay, entire families gathered around fires and wrapped themselves in blankets to stay warm.
"We barely made it out of the house," said Neset Guler, huddled around the fire with his four children. "Our situation is a disaster. We are hungry, we are thirsty. It's miserable."
The earthquake, which was followed by a series of aftershocks, was the biggest recorded worldwide by the US Geological Survey since a tremor in the remote South Atlantic in August 2021.
In Turkey, the death toll stood at 2,316, the Disaster and Emergency Management Authority (AFAD) said, making it the country's deadliest earthquake since an earthquake of similar magnitude in 1999 that killed more than 17,000. More than 13,000 were reported injured in Monday's quake.
At least 1,444 people were killed in Syria and about 3,500 injured, according to figures from the Damascus government and rescue workers in the northwestern region controlled by insurgents.
Poor internet connections and damaged roads between some of the worst-hit cities in Turkey's south, homes to millions of people, hindered efforts to assess and address the impact.
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.
"Everyone is putting their heart and soul into efforts although the winter season, cold weather and the earthquake happening during the night makes things more difficult," he said. He said 45 countries had offered to help the search and rescue efforts.
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 patients.
"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.
A top UN humanitarian official said fuel shortages and the harsh winter weather were also 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," UN resident coordinator El-Mostafa Benlamlih told Reuters in an interview via video link from Damascus.
In the government-controlled city of Aleppo, footage on Twitter showed two neighbouring buildings collapsing one after the other, filling streets with billowing dust.
Two residents of the city, which has been heavily damaged in the war, said the buildings had fallen in the hours after the quake, which was felt as far away as Cyprus and Lebanon.
Raed al-Saleh of the Syrian White Helmets, a rescue service in rebel-held territory known for pulling people from the ruins of buildings destroyed by air strikes, said they were in "a race against time to save the lives of those under the rubble."