(CNN) — At least 118 people were killed in two countries after one of the strongest earthquakes to hit Turkey in more than 100 years sent tremors across the region, collapsing buildings and sending residents running into the streets.

The 7.8-magnitude quake struck just after 4 a.m. Monday morning local time, 23 kilometers (14.2 miles) east of Nurdagi, Gaziantep province, at a depth of 24.1 kilometers (14.9 miles), the United States Geological Survey (USGS) said. Nurdagi is located along the Turkey-Syria border, and the quake was felt in several countries across the region, including Syria and Lebanon.

At least 76 people were killed and more than 440 injured in Turkey, according to the country’s disaster management agency AFAD. In neighboring Syria, at least 42 people died and around 200 more were injured, Syrian state run news agency SANA reported, citing a Health Ministry official.

In Syria, the deaths were reported in Aleppo, Hama and Latakia, SANA said. Dozens of people are trapped under rubble, according to the “White Helmets” group, officially known as Syria Civil Defense.

The quake struck before daybreak on Monday, when residents were likely asleep and unprepared for the impact. Video from Turkey shared on social media showed dozens of collapsed buildings, while frightened residents huddled on the darkened streets amid the chaos. Rescue workers can be seen conducting search-and-rescue operations by flashlight.

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, according to the USGS. Earthquakes of this magnitude are rare, with fewer than five occurring each year on average, anywhere in the world. Seven quakes with magnitude 7.0 or greater have struck Turkey in the past 25 years — but Monday’s is the most powerful.

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. “It’s a very large fault zone, but this is a larger earthquake than they’ve experienced any time in recent memory,” Lang said.

 

Searching for survivors

 

Search-and-rescue teams have been dispatched to the south of the country, Turkey’s interior minister, Suleyman Soylu, said. AFAD, the disaster agency, said it had requested international help through the Emergency Response Coordination Centre (ERCC), the European Union’s humanitarian program.

Nearly 1,000 search and rescue volunteers have been deployed from Turkey’s largest city, Istanbul, according to its governor Ali Yerlikaya.

“80 AFAD (emergency disaster agency) officers, 27 accredited municipalities and NGOs, 968 Search and Rescue volunteers, 4 K9 dogs, 2 trucks and aid materials have been sent to the area impacted by earthquake,” Yerlikaya wrote on Twitter.

“Sorry for our loss. I wish our injured a speedy recovery.”

Strong aftershocks have been felt in southern and central Turkey. About 11 minutes after the main quake hit, the strongest aftershock of 6.7-magnitude hit about 32 kilometers (20 miles) northwest of the main quake’s epicenter. Another intense aftershock with a magnitude of 5.6 then occurred 19 minutes after the main quake.

Journalist Eyad Kourdi, who lives in the city of Gaziantep, told CNN there were up to eight “very strong” aftershocks in under a minute after the 7.8 magnitude quake struck, causing belongings in his home to fall to the ground. Many of his neighbors had left their homes following the quake, he added.

The governor of Gaziantep, Davut Gul, said on Twitter that “the earthquake was felt strongly in our city,” and advised the public to wait outside their homes and stay calm.

“Please let’s wait outside without panic. Let’s not use our cars. Let’s not crowd the main roads. Let’s not keep the phones busy,” he said.

Gaziantep province has a number of small- and medium-sized cities, with a sizable refugee population, according to Brookings Institute fellow Asli Aydintasbas.

“Some of these areas are rather poor. Some are more richer, urban areas … but other parts that we’re talking about that seem to have been devastated, are relatively lower income areas,” she said.

Video from the city of Diyarbakir, to the northeast of Gaziantep, shows rescue workers frantically trying to pull survivors out of the rubble.

Turkish President Recep Tayyip Erdogan said the quake was felt in many parts of the country.

“I convey my best wishes to all our citizens who were affected by the earthquake that occurred in Kahramanmaraş and was felt in many parts of our country. All our relevant units are on alert under the coordination of AFAD,” Erdogan wrote on Twitter.

This is a breaking news story. More to come.

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