Istanbul, Turkey (BBN)-At least 10 people have been killed in an explosion in a district of Istanbul popular with tourists, the city authorities say.
The explosion occurred just after 10:00 local time (08:00 GMT) in the city's historic Sultanahmet district, close to the Blue Mosque, reports BBC.
Fifteen people were also wounded in the blast, the Istanbul Governor's Office said in a statement on its website.
Some reports suggest the explosion was caused by a suicide bomber.
Ambulances rushed to the scene and police have sealed off the area.
The BBC's Mark Lowen in Istanbul says in recent months there have been sporadic attacks by a far left group in Istanbul, while violence has soared between Turkish forces and PKK Kurdish militants, mainly in southeast Turkey, after a ceasefire broke down.
Turkey has also been hit by bomb attacks blamed by prosecutors on the so-called Islamic State group.
Two suicide blasts in the capital Ankara in October killed more than 100 people and more than 30 people were killed in an attack near the border with Syria in July.
BBN/SK/AD