A suspected suicide bombing has hit a busy shopping area popular with tourists and locals in Istanbul, killing at least five people.
Turkish media reported that several people were wounded in the blast in İstiklal Avenue, also known as Istiklal Street, but casualty figures could not immediately be confirmed.
An unconfirmed report from CNN Turk claimed at least three people were dead and seven injured after a possible suicide bombing, while other media but the death toll higher and said up to 20 bystanders were injured.
Helicopters and ambulances were seen converging on the scene as rescue efforts continued.
The wide pedestrianised avenue is one of the most famous streets in Istanbul, lined with boutiques, art galleries, theatres, cafes and foreign consulates, leading to Galatasaray Square.
Local residents said the area hits its peak on weekends afternoon and evenings and that 11am local time (9am GMT), when the blast hit, would have been comparatively quiet.
Growing speculation that the blast was another terror attack aimed at hitting Turkey's tourist industry and liberal social scene could not be confirmed and there was no immediate claim of responsibility.
The blast came after a bombing claimed by a Kurdish militant group killed 37 people in Ankara on Sunday and a suspected ISIS suicide bomber killed 13 tourists at Istanbul's Sultanahmet Square in January.
Germany closed its embassy in Ankara and a consulate and German school in Istanbul last week because of a warning over an imminent attack.
Both the Istanbul school and consulate are situated near Istiklal Street but it was unclear if the threat was linked to Saturday's attack.
/257