The huge rear-end collision occurred on the Diyarbakir-Sanliurfa highway.
"The temperature is two below zero and humidity is high," Diyarbakir Metropolitan Municipality said, adding that "the visibility has dropped to 50 metres due to thick fog".
Flights in Diyarbakir airport were also shut down due to the fog. In last few days, thick fog has swept across Turkey, disrupting many flights in Istanbul and Izmir.
--IANS (Posted on 07-01-2014)