Turkey was in turmoil early Saturday as a military coup unfolded, with no clarity about how widespread the putsch was or what its chances of success might be.
A "group within the armed forces have made an attempt to overthrow the democratically elected government outside the chain of command," said an official with the office of President Recep Tayyip Erdogan, who had clearly not been removed from office.
The official said an earlier Turkish military statement announcing a takeover was not issued by the top command, indicating that the coup might be the work of a splinter group of soldiers.
The website of the Turkish military was down, further raising questions about the identities of those behind the coup.
The earlier statement announcing the coup was read by an anchorwoman on state broadcaster TRT. She also announced that there was a curfew across the country until further notice, citing the need for people's safety.
Despite the curfew, the police - normally loyal to Erdogan - were not out on the streets of Istanbul.
There were reports of warplanes flying low over Istanbul, as well as shots and explosions throughout the metropolis.
Fighting also broke out in Ankara, with tanks on the streets, according to reports from CNN Turk and witnesses on the ground. Broadcaster NTV cited the state-run Anadolu news agency as saying 17 police were dead there.
Erdogan, who was reportedly in a safe location, telephoned broadcaster CNN Turk to say he remains president and the head of the army.
He blamed US-based Islamic preacher Fethullah Gulen for the power grab. Gulen and Erdogan were once allies in trying to bring Erdogan's mildly Islamic-rooted Justice and Development Party to power. However, since a split several years ago, Erdogan's forces have moved actively to dislodge Gulenists from power in Turkey.
Erdogan called for the people to take to the streets against the coup. Witnesses reported crowds chanting "Allah Akhbar" (Praise Allah) in the streets of Istanbul. Prayers were being called out from mosques in Istanbul, hours before scheduled morning prayers.
There were large-scale military deployments in Ankara and Istanbul, both on the ground and in the air. There were reports of shots fired in Ankara. The army reportedly took over the airport in Istanbul and stopped flights, according to Dogan, after partially closing bridges.
However, Dogan later reported that the military cleared out of the airport after a confrontation with Erdogan supporters.
Amid the turmoil, several international air carriers - including Lufthansa, Aeroflot and KLM - reported recalling flights that were on their way to Turkey.
Earlier, Turkish Prime Minister Binali Yildirim said on local television that there had been a coup "attempt" by elements within the military. He pledged that democracy would not be overthrown.
In 1997 the military forced the government from office in the "post-modern coup." The last full military takeover occurred in 1980, including suspension of the constitution.
The head of the largest opposition party in Turkey, Kemal Kalicdaroglu of the centre-left People's Republican Party (CHP), came out against the latest coup in a series of tweets, saying the country has "suffered a lot" in past military takeovers.
Celebratory gunfire and fireworks filled the skies in Syrian areas under the control of president Bashar al-Assad as news circulated that the Turkish military was attempting to overthrow President Recep Tayyip Erdogan, eyewitnesses in Damascus told dpa.
Erdogan has backed the Syrian uprising against al-Assad's regime since it started in 2011.
US President Barack Obama has been briefed on the apparent coup, National Security Council spokesman Ned Price says.
Obama also spoke to Secretary of State John Kerry, who is in Moscow, to assess the situation.
"The president and secretary agreed that all parties in Turkey should support the democratically elected government of Turkey, show restraint, and avoid any violence or bloodshed," read a White House statement.
Similar calls came from EU foreign policy chief Federica Mogherini and Iran.
Fars reported that two border crossings between Iran and Turkey had been shut down and that President Hassan Rowhani was planning a crisis meeting on the situation in Turkey.