A father and his young son were pulled alive from beneath the rubble of a collapsed building on Sunday after surviving four days trapped below following Venezuela's devastating 7.2 and 7.5 earthquakes, in a rescue hailed as nothing short of a miracle.

Rescue teams and local civilians had spent days searching the shattered remains of buildings in La Guaira state, one of the hardest-hit areas, where hopes of finding anyone else alive beneath the concrete had all but disappeared.

But after a burst of movement, a pair of dust-coated legs were pulled out of a hole.

Rescue crews from Virginia, France and Venezuela carefully pulled the father from a narrow gap in the debris, his limp body still clutching his cellphone as medics rushed to place him on a stretcher.

Moments later, his young son emerged shirtless and barely responsive. He was passed gently over a line of hard-hat-clad rescuers from Fairfax County Urban Search & Rescue toward a waiting ambulance.

'Slow, slow, gentle, gentle,' rescuers chanted in a mix of Spanish and English as the father and son were carried through a crowd of emotional onlookers and into a nearby ambulance.

As the pair reached safety, exhausted rescue workers broke into applause at a time when hope of finding survivors was rapidly fading.

Associated Press journalists Juan Pablo Arraez and Matías Delacroix were among those who witnessed the extraordinary rescue amid a mountain of rubble that lines swathes of the northern Venezuelan coast.

On Sunday, Arraez said they were scouring the La Guaira region 'trying to see if we can see any miracles' when they found the US rescue teams and local civilians calmly working to pull the father and son out of the building.

'At this stage many begin to lose hope. You see that in their faces,' Arraez said, as helicopters flew overhead.

'When somebody makes it out alive, this father and son. It's more than a glimpse, it's real hope for people.'

The  one-two punch of the earthquakes has been the greatest natural disaster the South American nation has faced in decades.

Authorities reported 1,450 people were dead on Sunday, with thousands more injured and many more missing.

The first 48 to 72 hours after a natural disaster are crucial to rescue efforts, though survival can be extended if people have access to food and water.

But small moments of optimism, solidarity and humanity like this have cut through almost overwhelming grief.

Venezuelan firefighters poured water into the mouth of a dust-covered dog peeking its head through cracks in the concrete.

After being trapped for 70 hours, one woman sat up on a stretcher, grinning and waving at cheering crowds as she was loaded on a gurney into an ambulance.

The Venezuelan government faced growing criticism from Venezuelans that its response was inadequate and overshadowed by civilian-led efforts to rescue people buried under collapsed buildings. Thousands more have been reported missing.

Venezuela's acting President Delcy Rodriguez said Sunday night that even as the threshold passed, the search for survivors would continue. 

More than 2,600 rescue workers from around the world had arrived with trained search dogs and machinery, the government said.

'It´s been incredibly hard work, but we're going strong,' said Jason Mercano, a civilian who was able to communicate with family buried under the rubble and was working with rescue teams to pull them out.

'We've never given up hope,' he added.

Still, many Venezuelans are struggling to hold onto hope in an increasingly desperate situation. 

The quakes  that hit last Wednesday have left a trail of devastation. The U.N. said up to 6.8 million of Venezuela's nearly 30 million residents may be affected.

A layer of dust coated coastal communities, and as the stench of decomposing bodies spread, more people began to wear masks.

Authorities said Sunday that more than 770 buildings had totally or partially collapsed from the earthquakes, twice as many as were reported destroyed or damaged on Friday. 

The risk of further damage remains as aftershocks continued to shake Venezuela; quakes measuring 4.2 and 4.5 hit Sunday morning.

But rescue efforts in La Guaira - the hardest-hit area - appeared significantly more organized on Sunday as international rescue missions arrived en masse. 

In previous days, residents there had expressed frustration and anger about the level of response.

The government reported on state television that more than 14,000 members of the military and police are now patrolling La Guaira state, where access is blocked and special permits are required to enter.

Because of the chaos and shoddy cellphone service since the earthquakes, many Venezuelans have turned to non-governmental digital databases to report their loved ones as missing. 

More than 50,000 people were reported missing on one such database, though it is unclear how many have been found.

In one part of La Guaira, Helen Guedez and her mother were reeling. They had spent days trying to save her father Jesús from their apartment.

She felt a swell of hope when rescue teams from the US had come to inspect the building and confirmed to them that her dad was still alive under the rubble. But they told the family that the building was too unstable to enter and rescue him, she said.

They left the scene, but Guedez said would continue to try and rescue their father without their assistance. She said they were now working with civilian volunteers and local miners to get him out.

'We're not going to give up,' said Guedez. 'The rest of the team is willing to continue. They know there's another way to get him out and they said they're going to keep working until the very end.'

Despite the overwhelming demand for medical services and the shortage of supplies in Venezuela´s public health system, Domingo Luciani Hospital in the capital of Caracas coped with an influx of patients thanks to a flood of donations.

'We have tons of patients, but thank god, people have responded by bringing us a great deal of supplies,' said Leomery Pérez, an anesthesiologist at the hospital.

Authorities said they had treated more than 3,100 wounded people, including many with crush injuries.

The disaster poses a significant challenge for acting President Rodriguez the former vice president who took office in January after the US capture and removal of then-President Nicolas Maduro.

Since then, the US government has played in increasingly powerful role in dictating the future of the South American nation. 

Venezuela has faced economic disarray for more than a decade, and many people reject the legitimacy of the political movement Rodríguez represents .

The country now faces an even more difficult circumstances, said Ronal Rodríguez, researcher for the Bogotá-based Venezuelan Observatory at the University of Rosario.

'There is political interference by the United States, the operational incompetence of a government that has driven the country into a complex humanitarian crisis and, all of the sudden, an earthquake in a place that lacks human capital and short-term resources to address the situation,' he said.

Amy Pope, director general from International Organization for Migration, warned that displacement from Venezuela - where crisis has forced 8 million people to migrate over the past decade - was likely to increase as people seek safety.

Rodríguez on Sunday said she was setting up a special commission to assess the damage to homes to confirm whether it's safe for people sleeping on the streets to return, adding that her government would also examine infrastructure damage. The search for life in the destruction, she said, would also continue.

'Today we recovered people who are still alive,' she said. 'We always maintain hope.'