A Turkish military combat helicopter crashed on Saturday in northwestern Syria's Afrin during the ongoing operation, and two soldiers were killed, Turkish Prime Minister Binali Yildirim said.It is not clear at this point whether the incident occurred due to an external intervention or not. An investigation has been launched, he told journalists in southwestern Mugla province, local TV channel CNN Turk reported.The Turkish helicopter was a T129 ATAK helicopter, confirmed Yildirim."We are looking into it. We are trying the determine the cause," he noted.In a statement, Turkish General Staff said an ATAK combat helicopter crashed around local time 1 p.m. during ongoing operation in Afrin. Technical investigation is underway.Earlier, Turkish President Recep Tayyip Erdogan said that the helicopter was downed in southern province of Hatay and that losses such as this incident were expected to happen in battle time.Speaking at a meeting of the ruling Justice and Development Party (AKP) in Istanbul, Erdogan said "we might lose one helicopter, but they will pay a heavier price."Turkey launched "Operation Olive Branch" on January 20 to clear People's Protection Units (YPG) militants, backed by the United States while considered by Ankara as "terrorist group," from Afrin in northwestern Syria.With the helicopter crash, the death toll of the Turkish Armed Forces increased to 20. More than 1,100 YPG militants have been killed, according to Turkish military.