Cold, hunger and despair gripped hundreds of thousands of people left homeless after the earthquakes that struck Turkey and Syria three days ago as the death toll passed 20,000 Thursday.
The rescue of a 2-year-old boy after 79 hours trapped in the rubble of a collapsed building in Hatay, Turkey, and several other people raised spirits among weary search crews. But hopes were fading that many more would be found alive in the ruins of towns and cities.
The first UN convoy carrying aid to stricken Syrians crossed over the border from Turkey.
Hundreds of thousands of people in both countries have been left homeless in the middle of winter. Many have camped out in makeshift shelters in supermarket car parks, mosques, roadsides or amid the ruins, often desperate for food, water and heat.
Some 40% of buildings in the Turkish city of Kahramanmaras, epicentre of the tremor, are damaged.
Authorities say some 6,500 buildings in Turkey collapsed and countless more were damaged.
The death toll in Turkey rose to 17,406, Health Minister Fahrettin Koca said. In Syria, already devastated by nearly 12 years of civil war, more than 3,300 people have died, according to the government and a rescue service in the rebel-held northwest.
Turkish officials say some 13.5mn people were affected in an area spanning roughly 450 km from Adana in the west to Diyarbakir in the east. In Syria, people were killed as far south as Hama, 250 km from the epicentre.
Many in Turkey have complained of a lack of equipment, expertise and support to rescue those trapped - sometimes even as they could hear cries for help.
President Erdogan said on a visit to the area on Wednesday that operations were now working normally and promised no one would be left homeless.
In Syria, relief efforts are complicated by a conflict that has partitioned the country and wrecked its infrastructure.