Images on Turkish television and social media showed rescuers digging through the rubble of levelled buildings in the city of Kahramanmaras and neighbouring Gaziantep.
A fire lit up the night sky in one image from Kahramanmaraş, although its origin remained unclear.
NTV television said buildings also crumbled in the cities of Adıyaman, Malatya and Diyarbakır.
CNN Turk television said the quake was also felt across parts of central Türkiye and the capital Ankara.
