The Turkish government says the suicide bomb attack in Istanbul on Saturday was carried out by a member of the self-proclaimed Islamic State organisation.
The explosion killed an Iranian and three Israelis – two of them dual American nationals – and wounded dozens of others in a shopping street popular with tourists.
The Israeli Prime Minister Benjamin Netanyahu has said his country is trying to determine whether the attack was aimed at its nationals.
The bomber who also died in the attack has been identified by the Turkish authorities as Mehmet Ozturk, who was born in 1992 and came from the southern province of Gaziantep.
“According to the information given to me, this person (who carried out the attack) is not on the list of people wanted by the police or gendarmerie. Up to now, five people have been detained,” said Turkey’s Interior Minister Efkan Ala, adding that seven provinces in the south were now under curfew.
The attack appeared similar to a suicide bombing in Istanbul in January, also blamed on ISIL, which killed several German tourists.
Turkey is part of the US-led coalition fighting the jihadists in Iraq and in Syria.
It is also battling Kurdish militants in the southeast and has blamed the PKK for attacks.
The TAK, an offshoot of the outlawed Kurdish group, claimed responsibility for recent bombings in Ankara.