BBC reports that Binali Yildirim, the Turkish Prime Minister, confirmed "illegal action" by a group within the Turkish military.
Bridges around Istanbul are closed and citizens reported seeing military aircraft flying low over Ankara. Traffic is completely stopped on the Bosphorus and Fatih Sultan Mehmet bridges in Istanbul.
Social media users are reporting that social media sites such as Facebook and Twitter are shut down in Istanbul, but this has not been confirmed.
All police in Ankara have been summed to duty by the Turkish government.
According to Reuters, the Turkish Prime Minister says that the government is still in control in both cities. Yildirim told NTV television by telephone: "We are working on the possibility of an attempt. We will not allow this attempt."
"Those who are in this illegal act will pay the highest price"