A powerful earthquake has hit Gaziantep in south-eastern Turkey, near the border with Syria, killing at least five people.
The US Geological Survey said the 7.8 magnitude tremor struck at 04:17 local time (01:17 GMT) at a depth of 17.9km (11 miles) near the city of Gaziantep.
The quake was felt in the capital Ankara and other Turkish cities, and also across the wider region.
Many buildings have collapsed, and there are reports of people trapped.
Turkish Interior Minister Suleymon Soylu said 10 cities were affected: Gaziantep, Kahramanmaras, Hatay, Osmaniye, Adiyaman, Malatya, Sanliurfa, Adana, Diyarbakir and Kilis.
A BBC Turkish correspondent in Diyarbakir, north-east of Gaziantep, reported that a shopping mall in the city collapsed.
The tremor was also felt in Syria, Lebanon and Cyprus.
Rushdi Abualouf, a BBC producer in the Gaza Strip, said there was about 45 seconds of shaking in the house he was staying in.
Turkish seismologists estimated the strength of the quake to be 7.4 magnitude.
They said that a second tremor hit the region just minutes later.
Turkey lies in one of the world's most active earthquake zones.
In 1999, more than 17,000 people were killed after a powerful tremor rocked the north-west of the country.