Sections of the Turkish army have officially declared a coup and martial law, saying they have “taken control of the country” as Istanbul’s main airport was closed and fighter jets were seen in the skies.

President Recep Tayyip Erdogan in a phone call to broadcaster CNN Turk said he remained the president of the country and the head of the army and called for people to take to the streets against the coup.

“We will overcome this,” Erdogan said, speaking on a video call to a mobile phone held up to the camera by a presenter. He called on his followers to take to the streets to defend his government and said the coup plotters would pay a heavy price.

Meantime flights to Atatürk airport have been cancelled while curfew has been imposed till Saturday morning.

An official said Erdogan was speaking from Marmaris on the Turkish coast where he was on holiday. Erdogan said he would swiftly return to Ankara.

In the capital Ankara, gunshots were heard, as military jets and helicopters were seen flying overhead, a Reuters news agency witness said. The state-run Anadolu Agency reported that a military helicopter had attacked the Ankara police headquarters and Reuters said the parliament was surrounded with tanks.

Another Reuters witness reported hearing gunfire at Istanbul airport.  An Al Jazeera correspondent in the coastal city of Izmir reported an unusually heavy military build-up in the city ahead of the coup attempt.

In Gaziantep, a city in the south, Al Jazeera’s Zeina Khodr reported that supporters of Erdogan had taken to the streets, heeding his call for people to protest. Cars streamed towards the airport.

The Dogan news agency quoted the military members on Friday as saying that they wanted “to reinstall the constitutional order, democracy, human rights and freedoms, to ensure that the rule of law once again reigns in the country, for the law and order to be reinstated”.

The statement went on to say that “all international agreements and commitments will remain. We pledge that good relations with all world countries will continue”.

Earlier, speaking on television, Turkish Prime Minister Binali Yildirim said that a number of generals were involved in what he called an attempted coup.

He vowed that the “perpetrators” would be contained, adding that the government would “never give up democracy”.

Al Jazeera has learned that Istanbul’s Ataturk international airport has been shut down and all flights have been cancelled.

An Al Jazeera reporter in Istanbul reported seeing military officers arriving at the central Taksim Square, and ordering everyone to leave.

“They were evacuating the entire square,” our reporter said. “People are going home now.”

Separately, a TRT World reporter told Al Jazeera that soldiers had entered the government-funded television network’s building, ordered the channel off the air and taken the phones of staff members.

‘Dissent in the military’

Istanbul’s Bosphorus Bridge and Fatih Sultan Mehmet Bridge were also been shut down by the army, local television channels reported. The two major bridges connect the Asian side of Istanbul to the European side.

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

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

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

Turkey has had a history of coup attempts, the last in 1997, which forced the resignation of then-prime minister Nemettin Erbakan. – Source: Al Jazeera and agencies