A large explosion has struck outside a police station in Istanbul, with witnesses reporting the sound of gunfire.
Vasip Şahin, the governor of Istanbul, said a motorbike bomb was source of the blast in the Turkish city's Yenibosna district on Thursday afternoon.
A witness in a nearby school told the Daily Sabah newspaper gunshots were heard after the explosion, while another at a bus station 500 metres away felt the ground shake with the force of the blast.
Several people were injured, with at least one taken to hospital for treatment, with photographs of the scene showing the road strewn with debris and several cars and vans with their windows smashed and bodywork dented by shrapnel.
Mr Şahin said the attack struck Fatih Street, which leads to a mosque along an avenue of busy shops and cafes.
There was no immediate claim of responsibility from militant groups.
Turkey has been the target of a string of attack by both Isis and Kurdish separatists in recent months.
Islamists have attacked tourists and protestsers in Istanbul and Ankara, as well as launching suicide bombings in areas near the Syrian border.
Kurdish militant groups have more frequently targeted police and the Turkish armed forces, who are currently carrying out operations against the separatist Kurdistan Workers' Party (PKK) in the south-east as a three-decade insurgency continues.
Another group, the Kurdistan Freedom Falcons (TAK) have also claimed responsibility for attacks including a car bombing that killed 37 people in Ankara in March.
