Rescue teams in Turkey and Syria were racing to find survivors as the most severe earthquake in 80 years devastated towns and cities across the region, leaving almost 5,000 people dead and more than 20,000 wounded.

On Tuesday, authorities were pulling people out of the rubble in freezing temperatures in south-eastern Turkey and north-western Syria, where there was sporadic snowfall.

More than 10,000 people and thousands of pieces of heavy machinery were engaged in the rescue effort, with aid organisations rushing to provide basic necessities and calling for blood donors as the humanitarian toll mounted. Poor weather, bad road conditions and congestion at airports snarled the rescue work.

The effort came after a 7.8 magnitude earthquake struck near the city of Gaziantep, Turkey, early on Monday, toppling thousands of buildings over a vast area. More than 300 aftershocks continued to rumble through the region following the initial quake, according to Fuat Oktay, Turkey’s vice-president.

The death toll in Turkey reached 3,419 people, with 20,426 injured, according to the country’s disaster relief agency Afad. At least 769 people were killed in government-held areas in Syria, with more than 1,448 injured, according to the country’s health ministry. In the rebel-held north-west, more than 790 people died and in excess of 2,200 were injured, according the Syria Civil Defence, the aid workers also known as the White Helmets. The total confirmed death toll across the two countries stands at 4,940.

Experts said the low quality of buildings in the region and lack of resilience to earthquakes contributed to the huge destruction. Many buildings were “not designed from seismic considerations to absorb this much ground motion”, said Kishor Jaiswal, a scientist at the US Geological Survey.

“It’s difficult to watch this tragedy unfold, especially since we’ve known for a long time about how poorly the buildings in the region tend to behave in earthquakes,” he added.

Turkey’s Red Crescent aid group said it was shipping emergency supplies “nonstop”, with almost 2,000 tents and 27,000 blankets in addition to mobile kitchens and catering facilities reaching the affected area.

Teams of Turkish rescue workers have been filtering through Istanbul’s main airport since Monday, many sleeping on the floor and resting their heads on helmets and sleeping bags while waiting for flights.

Different Turkish aid groups were heading to cities including Adana, to join efforts to clear the rubble and rescue those trapped under it.

“We have to do everything we can to help,” said Sinan Aksoy, 34, a firefighter who was on his way to the southern city with a group of about 50 volunteers. “We’re running against time to find people alive.” 

Turkey’s central bank ordered local lenders not to charge transaction fees on fund transfers to accounts collecting earthquake relief donations and eased conditions on certain types of credit extended to companies in the stricken region.