"There is no evidence that it was downed by an outside intervention", Yildirim said.
Turkish Prime Minister Binali Yildirim announced the deaths in a televised address on Saturday.
The state-run Anadolu agency, citing the Turkish army, said the ATAK aircraft crashed at around 1pm local time (10:00 GMT).More news: North Korea stages show of force with new missiles during parade
"A little while ago, one of our helicopters was downed", Erdogan said. "We might lose a helicopter, but they'll pay the price for this", he said in Istanbul.
The Turkish army confirmed the crash but did not comment on a cause.
The Afrin invasion, launched on 20 January, aims to the prevent the YPG from establishing a statelet on Turkey's borders, which they fear could become a base for PKK attacks in Turkey.
The operation is being carried out under the framework of Turkey's rights based on global law, UN Security Council resolutions, its self-defense rights under the UN charter, and respect for Syria's territorial integrity, it said.More news: Winter Olympics 2018: Snowboarder Red Gerard wins Team USA's first gold medal
Turkey has long fought Kurdish unrest in the southeastern part of the country. Calling for "urgent worldwide action" to protect civilians, Zeid also slammed what he called an "epic failure of global diplomacy" to end the seven-year-old war.
The U.S.'s Syria policy, especially its military support for the Syrian Democratic Forces (SDF), which is dominated by YPG terrorists, has been a cause of tension between the two North Atlantic Treaty Organisation allies.
Turkey said it launched the operation to target "terrorist organizations", including YPG forces.
Turkish authorities on Friday issued an arrest warrant against Kemalbay and 16 other HDP officials for issuing calls for mass protests against Ankara's military offensive in the Kurdish-held area of Afrin in northern Syria, according to state media.More news: The reasons North Korean athletes won't defect
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