17 police officers killed in helicopter attack on police special forces headquarters in outskirts of Ankara, Anadolu Agency reported.
President Recep Tayyip Erdoğan said in a phone interview on broadcaster CNNTürk that a "minority group" in the military has attempted a coup.
Erdoğan said the parallel state, referring to the followers of the U.S.-based scholar Fethullah Gülen, has promoted the attempt.
"We will not leave the ground to them," he said, vowing to end the "occupation" by the group, called on nation to unite at squares and airports. Erdoğen said he would also be on the streets.
The move is not as part of the chain of command, he said.
"I am the chief commander," he said.