At least 10 people were killed and several others injured in an explosion at central Istanbul's Sultanahmet square, a major tourist spot.
Eyewitness said the explosion was very loud. "We shook a lot. We ran out and saw body parts," a woman who works at a nearby antiques store said.
A video footage on CNN Turk channel showed police and ambulance at the scene.
Turkish media quoted the office of Istanbul’s governor as saying that at least 15 people have been injured in the blast and rescue teams and ambulances have reached the spot.
The governor's office said that the cause of blast has not yet been ascertained and the investigation is on.
However, an official said on condition of anonymity that a suicide bomber may be responsible for the explosion.
Tourists were among the victims of the explosion, reports indicate, while wounded persons were transferred to nearby hospitals, mainly Haseki Training and Research Hospital.
"The explosion was so loud, the ground shook. There was a very heavy smell that burned my nose. I started running away with my daughter. We went into a nearby building and stayed there for half an hour. It was really scary," a German tourist was quoted as saying by news agencies.
Turkey has also become a target for terrorists, with two bombings last year blamed on the radical Islamic State group, in the town of Suruc near the Syrian border and in the capital Ankara, the latter killing more than 100 people.
Kurdish, leftist and Islamist militants have all carried out attacks in Turkey in the past.
