Turkish military coup attempt by army faction underway
Troops took to the streets in Istanbul and Ankara as jets flew low overhead as martial law was enforced in the country.
President Erdogan who had been taken to "a safe place" called on the people to take to the street to support the government and democracy.
"We are working on the possibility of an attempt. We will not allow this attempt," he told NTV television during a Facetime call.
"Those who are in this illegal act will pay the highest price," he added, saying it would not be correct to describe the move as a "coup".
There four main army divisions in Turkey with the biggest one based in Istanbul. The commander of the unit said he does not support the coup and troops have left the city's international airport, which had been blockaded by the military.
In Istanbul, people began to mass on the streets to support the government. There were reports of gunfire between rival army units in the city's Taksim Square.
Other opposition parties have issued statements condemning the coup against the government and "democracy".
Turkey's intelligence issued a statement telling people not to "give in to the coup".
Turkey's new Prime Minister Binali Yildirim denounced what he said was an "illegal attempt" by elements in the military.
The military faction took over state media outlet TRT and it is unclear which parts of the Turkish national infrastructure is under their control or the number of troops behind the coup.
"The power in the country has been seized in its entirety," said a military statement quoted by Turkish media.
"[We have done this] in order to ensure and restore constitutional order, democracy, human rights and freedoms and let the supremacy law in the country prevail, to restore order which was disrupted."
It is not clear who the army faction could be linked to, but analysts have suggested they could be ultra-nationalists or linked to US-based Tethuallah Gullen, a long-time critic of Erdogan.
Television pictures showed tanks deployed outside Ataturk airport in Istanbul. Reports said that flights into the airport had been halted.
Turkey has a history of coups with governments ousted on three occasions in the last decades by full military coups.
However analysts had usually assumed that the ruling Justice and Development Party (AKP) of President Recep Tayyip Erdogan had good relations with the military.
Turkey's top general was reportedly taken hostage at the military headquarters in the capital Ankara after the attempt, the state-run Anadolu news agency reported.
"General Hulusi Akar has been taken hostage by a group in the military who attempted an uprising," the agency said citing "credible sources".
US Secretary of State John Kerry said he hoped for "peace and continuity" in Turkey.
Turkish security forces on Friday partially shut down the two bridges across the Bosphorus Strait in Istanbul as military jets were heard flying low over Ankara, reports and AFP correspondents said.
The Bosphorus and Fatih bridges were closed by the gendarmerie - a branch of the Turkish military dedicated to internal security - for traffic travelling from Asia to Europe, NTV television said.
Agencies contributed to this story.