Turkey's defense ministry said on Tuesday that a C-130 military cargo plane that crashed near the Azerbaijan-Georgia border had 20 Turkish personnel on board, including the flight crew.
It said search and rescue efforts continued, but did not provide any additional details on possible passengers from other nationalities or the cause of the crash.
Turkish President Tayyip Erdogan to offer condolences for "our martyrs" as search and rescue crews headed for the scene.
Turkey's defense ministry announced the crash, near Georgia's border with Azerbaijan, and said it was coordinating with Georgian authorities to reach the site.
While finishing a speech in Ankara, Erdogan was handed a note by his aides, after which he said he was saddened to hear about the plane's crash.
"God willing, we will overcome this crash with minimum hardships. May God rest the soul of our martyrs, and let us be with them through our prayers," he said.
The cause of the plane crash is unknown
Erdogan, his office, and the ministry did not say what caused the crash, and they did not provide the number of casualties. Local media said, without citing numbers, that there were both Turkish and Azeri personnel on board.
Interior Minister Ali Yerlikaya said he had spoken by phone to his Georgian counterpart, adding the Georgian minister was en route to the crash site.
This is a developing story.