A predawn earthquake with a magnitude of 7.7 hit the Turkish city of Gaziantep on Monday morning and a second measured at 7.6 struck nearby just nine hours later, according to Turkey’s disaster response management agency, known as AFAD.

Millions are facing a night without heating gas, electricity or fuel for their cars. Authorities halted flows of crude to a regional export terminal as they searched for signs of damage along a major oil pipeline.

“We are desperately waiting for help from neighboring provinces but they are not coming because they’ve also been hit badly,” 48-year-old Murat Gencogullari said by phone from the border province of Hatay. Several buildings had collapsed in the area, burying people under tons of concrete and twisted metal, he said. “Local authorities are struggling to cope but the damage is so widespread and heavy.”

President Recep Tayyip Erdoğan said Turkey is facing “the strongest disaster in a century”. Speaking before the second quake, he said it was impossible to speculate about the final death toll. Turkey later declared seven days of mourning.

The count stood at more than 1,600 in Turkey late Monday, according to AFAD, with more than 11,000 injured. In Syria, the tally of fatalities was about 540 in government-held areas, the AP said. Groups in the rebel-held northwest said the toll was at least 380.

At least four Turkish airports were damaged, said authorities, who were tracking calls for help on social media from people who were believed to be trapped under the rubble. More than 2,800 buildings have collapsed in Turkey, Erdogan said.

Among those affected were many of Turkey’s 3.7 million registered Syrian refugees, the biggest such population in the world.

Turkey stopped oil flows to Ceyhan export terminal on the Mediterranean coast as a precaution, although no leaks were detected on the pipelines feeding crude to the facility, according to an official with direct knowledge of the matter. Iraqi Kurdistan suspended oil exports through Turkey to the terminal, the Ministry of Natural Resources in Kurdistan said.

Ceyhan is a vital hub for oil sales from northern Iraq and Azerbaijan. The port exported over 1 million barrels a day in January, or 1% of global oil supplies. The shutdown helped push up prices on Monday.

US President Joe Biden and other world leaders offered condolences. Biden said the US deployed teams to support Turkey’s search-and-rescue operations, and “US-supported humanitarian partners are also responding to the destruction in Syria.”

Fault Lines

Turkey lies in one of the world’s most active seismic zones and is crossed by numerous fault lines. The disaster affected several southern Turkish provinces stretching hundreds of kilometres, where about 13 million people are bracing for colder winter temperatures. Erdoğan, who is facing general elections in May, dispatched several Cabinet ministers to the area.

Some parts of the local gas network were hit, stopping supply to Gaziantep, Hatay and Kahramanmaras provinces, Turkish state pipeline company Botas said.

Turkey hopes to restore gas flows within 48 hours, the Turkish official with direct knowledge of the matter said, speaking on condition of anonymity.

The first quake was felt as far away as Egypt and Cyprus. It was the worst in Turkey since a 1939 earthquake that killed about 33,000 people.

In 1999, tremors months apart hit Turkey’s industrial hub near Turkey’s largest city, Istanbul, and killed more than 18,000 people. That disaster overwhelmed the center-left coalition in charge at the time, paving the way for a deep financial crisis that helped Erdogan’s AK Party come to power. On Monday, Erdogan mobilized 9,000 first-responders and said Turkey is looking to receive help from 45 countries, along with the Nato and the European Union.

Turkey’s stock exchange Borsa Istanbul halted trading of some stocks and the main index fell as much as 4.5%. The Turkish lira was little changed at 18.83 per dollar.

The quakes hit areas that generate about 1/10 of Turkey’s national income, damaging airports in Adiyaman, Kahramanmaras, Malatya and Hatay. Some hospitals and a port also partially collapsed in Hatay, authorities said. Highways were also damaged.

“Erdoğan is likely to respond forcefully to limit the economic impact of the earthquakes,” Emre Peker, Europe director for Eurasia Group, said in an emailed note on Monday. “Relief measures are likely to follow in the form of large-scale and direct fiscal support, as well as new targeted credit-easing measures. These will also support the government’s standing in public opinion,” ahead of elections.

(With assistance from Patrick Sykes, Beril Akman, Tugce Ozsoy and Hayley Warren.)