By BBC News
Two explosions near a football stadium in Istanbul, Turkey, have killed at least 44 people and wounded 155 people, reports say.
Interior Minister Suleyman Soylu said it was thought a car bomb had specifically targeted riot police.
Witnesses heard gunfire after the attack, and ambulances and police vehicles rushed to the scene.
Police arrive at the site of an explosion in central Istanbul, Turkey, December 10, 2016. © Murad Sezer / Reuters
Turkey has seen a recent spate of militant attacks in major cities that have left dozens of people dead.
No group has said it was behind the attack but a wave of bombings in Turkey this year has been carried out by Kurdish militants and so-called Islamic State (IS), the BBC's Turkey correspondent, Mark Lowen, reports.
The fact that police appear to have been hit will focus suspicion on Kurdish guerrilla groups, who have mainly targeted the security forces, he adds.
Transport Minister Ahmet Arslan wrote on Twitter that it was a terror attack.
It happened two hours after a football match at the Vodafone Arena between Besiktas and Bursaspor, two of Turkey's top teams, ended.
Local media reported that fans had already dispersed. Bursaspor posted on Twitter that none of its fan groups knew of any injured fans.
Mr Soylu said: "It is thought to be a car bomb at a point where our special forces police were located, right after the match at the exit where Bursaspor fans exited, after the fans had left."
Turkish policemen at the site of an explosion in central Istanbul, Turkey, December 10, 2016. © Murad Sezer / Reuters
A police helicopter circled overhead and windows in nearby buildings were blown out by the force of the blasts.