Vasip Sahin, the governor for Istanbul, told reporters at the scene in Yenibosna area that none of those injured are in a serious condition - retracting an earlier statement that one person was seriously hurt.

There was no immediate claim of responsibility for the blast, which could be heard from the city's nearby Ataturk Airport. Mr Sahin said the investigation is ongoing.

The private Dogan news agency said police are searching for a person spotted leaving the scene carrying a motorcycle helmet.

Turkey has been rocked by a wave of deadly bomb attacks in the past year carried out by Kurdish rebels or Islamic State group militants.

The Kurdistan Workers' Party, or PKK, which has been waging a three-decade insurgency, has been targeting police and military in its campaign for Kurdish autonomy in south-east Turkey.

A fragile two-and-a-half-year ceasefire between Turkey and the PKK collapsed last summer. Since then, more than 600 Turkish security personnel and thousands of PKK militants have been killed in clashes, according to the state-run Anadolu Agency.

Rights groups say hundreds of civilians have also been killed in the clashes.