At least 20 people have been injured in an explosion near a football stadium in Istanbul, authorities have said.
Broadcaster NTV said 38 people had been wounded but gave no details of any death toll.
At least 20 people beeb injured, the Interior Minister said.
Two witnesses told Reuters they had heard two blasts outside the Vodafone Arena, which lies on the edge of the Bosphorus in central Istanbul and is home to the Besiktas soccer team.
Witnesses said police were deployed and had cordoned off the area as smoke rose from the newly built Besiktas Stadium.
Images and TV footage showed what appeared to be the burnt-out shell of a auto near the Vodafone Arena, with Turkish interior minister Suleyman Soylu indicating that it had targeted a riot police bus.
"We condemn the vile terror attack in Besiktas, Istanbul and wish quick recoveries to the injured", Transportation Minister Ahmet Arslan tweeted shortly after the blasts.
Speaking later to reporters in Istanbul, he said the first explosion took place on a hill adjacent to and overlooking the stadium.
Turkey has been hit by a series of bombings in recent years, some blamed on Islamic State militants, others claimed by Kurdish and far-leftist militant groups. God willing, we hope there won't be any.
Images broadcast on television showed more than a dozen ambulances on a street hugging the stadium and a police helicopter flying overhead with its search lights on. Investigators, including Istanbul Police Chief Mustafa Caliskan, were quickly on the scene.
"A vehicle packed with explosives is believed to have exploded where our riot squad was deployed shortly after the football fans dispersed following the match", Soylu said.
The Besiktas sports club "strongly condemned" terrorism and the attack in a statement posted on its website.
Prime Minister Binali Yildirim and Istanbul Governor Vasip Sahin were also notified about the attack, Anadolu said.