More than 4,300 dead in Turkey and Syria after earthquake.

(cnn) ⸻ More than 4,300 people have died and rescuers are racing to pull survivors from beneath the rubble after a devastating earthquake ripped through Turkey and Syria, leaving destruction and debris on each side of the border. The strongest earthquake to hit the region in a century shook residents from their beds at around 4 a.m. on Monday, sending tremors as far away as Lebanon and Israel. In Turkey, at least 2,921 people were killed and more than 15,800 others injured, according to Turkey's head of disaster services. In neighboring Syria, at least 1,451 people have died across government-controlled areas, mostly in the regions of Aleppo, Hama, Latakia, and Tartus. The "White Helmets" group, officially known as the Syria Civil Defense, reported 740 deaths in opposition-controlled areas. A host of countries have sent rescue workers to help the stricken region, where a colossal effort to find and free trapped civilians is underway. Monday's quake is believed to be the strongest to hit Turkey since 1939, when an earthquake of the same magnitude killed 30,000 people. Earthquakes of this magnitude are rare, with fewer than five occurring each year on average, anywhere in the world. Karl Lang, an assistant professor at Georgia Tech University's School of Earth and Atmospheric Sciences, told CNN the area hit by the quake Monday is prone to seismic activity, but this is a larger earthquake than they've experienced any time in recent memory. Eyad Kourdi, a CNN producer in Gaziantep, was staying with his parents when the earthquake struck early Monday. He and his parents waited outside in the rain for about 30 minutes before he could go back inside to grab coats and boots. Aftershocks have been felt in southern and central Turkey, with an aftershock of 6.7 magnitude hitting 32 kilometers (20 miles) northwest of the main quake's epicenter. Kourdi described Monday's aftershocks as being "like Armageddon." He also visited Pazarcik, a neighboring town, and said that the situation there "were even more catastrophic." Photos showing the true scale of the disaster emerged as day broke in Turkey, with entire buildings flattened, with metal rods scattered across the streets. Gaziantep Castle has been heavily damaged. A winter storm in the region is exacerbating the disaster, with hundreds of thousands of people impacted by this. More than 4 million people rely on humanitarian assistance in the region of northwest Syria where the deadly earthquake struck, according to the UN Office for the Coordination of Humanitarian Affairs (OCHA). Along with the devastation from the earthquake, Syrian communities are battling an ongoing cholera outbreak amid a harsh winter with heavy rain and snow over the weekend. Eyewitnesses in northwest Syria tell CNN the conditions in the aftermath of the quake are "terrifying" and "entire families dead" and "survivors sleeping on the streets in the freezing cold". Dr. Mostafa Edo, a Country Director for the U.S.-based NGO MedGlobal, said that his colleagues, who he had worked with for more than five years, was killed about two years ago in Russian airstrikes. Khalil Ashawi, a photojournalist based in Jindayris in Syria's northwest, says that in his ten years of covering war in Syria, he hasn't witnessed scenes as "disastrous" as the ones he did on Monday. The quake damaged several archeological sites in Syria, including Imam Ismail Mosque and the Shmemis Castle in the Hama Governorate, and the 13th century Aleppo Citadel. Search and rescue teams have been dispatched to the south of the country, Turkey's interior minister, Suleyman Soylu, said. Nearly 1,000 search and rescue volunteers have been deployed from Turkey's largest city, Istanbul, along with dogs, trucks and helicopters. Turkish President Recep Tayyip Erdogan announced that NATO, the European Union and dozens of other countries had offered to help after a deadly earthquake struck the city of Kahramanmaraş. The governor of Gaziantep, Davut Gul, advised the public to wait outside their homes and stay calm. Video from the city of Diyarbakir shows rescue workers frantically trying to pull survivors out of the rubble. Erdogan said the quake was felt in many parts of the country and all relevant units are on alert under the coordination of AFAD. Messages of condolences and support started pouring in Monday morning as world leaders woke to the news of the deadly earthquake. White House National Security Adviser Jake Sullivan said the United States was "profoundly concerned" about the destruction in Syria and Turkey and was ready to provide any and all needed assistance.