Turkish warplanes are reported to have shot down an unidentified military aircraft near the border with Syria.
A Turkish military official told the Reuters news agency that Turkish F-16s had fired on the jet after warning it that it was violating Turkish airspace.
Turkish media broadcast video footage of a plane crashing into mountains near the border with Hatay province.
Syrian and Russian military aircraft have been targeting jihadist militants and Western-backed rebels in the area.