Turkish Prime Minister Binali Yildirim has announced that a group of military forces have engaged in a "coup attempt" against the government.

Yildirim made the announcement late on Friday, as he vowed that the "perpetrators" will be contained.

He said that a number of generals are involved in the takeover of the government, adding that it "will never give up democracy".

"It seems there is dissent in the military ranks," Al Jazeera's Zeina Khodr, reporting from Gaziantep, said.

Istanbul's Bosphorus Bridge and Fatih Sultan Mehmet Bridge have reportedly been shut down by the Turkish army, local television channels reported, without giving a reason.

Dogan News Agency footage showed cars and buses being diverted, according to Reuters.

Reuters witnesses in Istanbul, Turkey's largest city, also spotted helicopters overhead.

In the capital Ankara, gunshots were heard, as military jets and helicopters were seen flying overhead, a Reuters witness said.

Turkey has had a history of coup attempts, the last time being carried out in 1997, which forced the resignation of then-prime minister Nemettin Erbakan