(NewsNation) — Rescue workers are still working to find survivors after two major earthquakes hit Turkey and Syria, even as the death toll tops 11,000.

The first 7.8 quake hit on Monday, followed within a few hours by a second 7.7 quake a few hours later. The World Heath Organization is already anticipating the death toll will reach 20,000. The number dead has surpassed the previous deadliest earthquake, a magnitude 7.8 earthquake in Nepal in 2015 which killed more than 8,800 people.

Project Hope Director of Emergency Preparedness and Response Arlen Fuller joined NewsNation to discuss the rescue operations that are underway.

Fuller said the destruction is unimaginable.

“We’re talking about thosands of buildings that have collapsed, full city blocks that are down. On top of that, we are in the middle of winter in Turkey. And so there’s snow on the ground with freezing temperatures and people are being forced outside,” he said.

Experts said the survival window for those trapped under the rubble of collapsed buildings or otherwise unable to access water, food, protection from the elements or medical attention was closing rapidly. At the same time, they said it was too soon to abandon hope for more rescues.

Project Hope has sent a canine rescue team in to help, and Fuller said it’s still possible for more survivors to be located.

“We’ve been in situations before with earthquakes, in which people, days after the earthquake, emerge and are alive,” Fuller said.

The Associated Press contributed to this report.