Turkish troops have reportedly shut down Ataturk airport and blocked the Bosphorus Bridge in Istanbul, one of two main links between the European and Asian landmasses.
There are reports of explosions in the country's capital of Ankara where jets and helicopters have been spotted flying low.
A crowd has been gathering in Taksim Square in central Istanbul where troops and police are already present
Military personnel and troops have occupying other key areas including the ruling AK party's headquarters.
Local TV channels have shown soldiers wearing full battle dress, with rifles and helmets dispersing in different parts of the city.
Turkish presidential sources have said senior military leadership were not been involved in this attempted coup.
Military troops have taken control of the state news channel TRT, according to Reuters news agency.
After a military statement was read out, TRT has gone off air.
Pictures claim to show police officers being detained by soldiers in Istanbul.
In addition, a video purporting to show a helicopter opening fire has surfaced on social media.
The Dogan news agency says one-way traffic on the Bosporus and Fatih Sultan Mehmet bridges were blocked. Video footage showed the bridge being blocked by military vehicles.
Dorian Jones, a British journalist, told Sky News: “Tanks are seen in the streets. There are reports of clashes between the police and the army.”
“I have been speaking to various friends across the city, some are reporting that they are hearing gunfire in the streets.”
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