“The attacker has been formally identified. He is linked to the terrorist organisation Daesh (ISIS),” Ala told a press conference.

Ala named the bomber as Mehmet Ozturk from Gaziantep, a southeastern city on Turkey’s border with Syria.

Three Israelis and one Iranian were killed, and 39 people injured, when the bomber blew himself up Saturday on Istiklal Caddesi, a bustling pedestrian street and popular meeting spot in the heart of the city.

No group has claimed responsibility for the attack.

Most of those injured in the blast on the pavement, outside a local government building, were also foreigners.

By Sunday morning, 19 people were still being treated in hospital, eight of them in critical condition, the health ministry said.

Ozturk, who was born in 1992, was identified by DNA traces found at the scene, Dogan news agency reported.

He was “not on our wanted list,” Ala said, defending the authorities against accusations of repeated security failings following six major attacks since July that have killed over 200 people.

Another alleged ISIS member, Savas Yildiz, had been initially named by Turkish media as the suspected bomber.

The minister said five people had been arrested on suspicion of links to the attack. Dogan reported that Ozturk’s father and brother were among those held.

Israeli media said the three Israeli victims – Avraham Goldman, 69, Jonathan Shor, 40 and Simha Damari, 60 – were part of a group that was on a gastronomic tour of Turkey. Two of them also had U.S. citizenship.

The bodies of the three Israelis were to be flown home Sunday for burial aboard an Israeli military jet, Israeli military sources said.

Five injured Israelis were repatriated overnight, Israel’s emergency services said.

– Government accused of ‘incompetence’ –

The Istanbul blast came just six days after 35 people were killed in a suicide car bombing in a busy square in the capital Ankara, in an attack claimed by Kurdish rebels.

“Terrorism will not win!” the defiant front page headline of pro-government newspaper Sabah read on Sunday.

The main opposition newspaper Cumhuriyet said the latest strike was proof of the government’s “incompetence” in its handling of the security crisis.

Ankara had borne the brunt of the attacks until now, being hit three times in five months.

ISIS was held responsible for Turkey’s worst ever attack, which killed 103 people at an October rally in Ankara in support of the Kurdish minority – arch-enemies of ISIS across the border in Syria.

The only attack in Istanbul since the summer, also blamed on ISIS, targeted the tourist quarter of Sultanahmet. Twelve German tourists were killed in that blast.

– ‘Terrifying’ new reality –

On Sunday morning, Istiklal Caddesi street and nearby Taksim Square, the nerve center of the European side of Istanbul, were eerily quiet, reflecting Turks’ growing nervousness in the face of the seemingly indiscriminate nature of the terrorist threat.

“You never know here it can happen. It’s terrifying,” said Ismail, a chef from a nearby restaurant.

Flowers, candles and hand-made placards calling for people not to be cowed by terrorism were left at the spot where the bomber struck.

Prime Minister Ahmet promised a determined fight “until all forms of terrorism are eradicated.”

The US and Europe, NATO allies which have been critical recently of Turkey’s slide into authoritarianism under strongman President Recep Tayyip Erdogan, assured the country of their support.

Erdogan has been accused of neglecting the fight against ISIS to wage a relentless offensive against the outlawed Kurdistan Workers Party (PKK) since a two-year-old truce between the state and the Kurdish rebels fell apart in July.

A Kurdish rebel group, the Kurdistan Freedom Falcons (TAK), claimed responsibility for the March 13 suicide car bombing in Ankara, saying it was avenging the military’s actions in the battle-scarred towns of the mainly Kurdish southeast.

TAK, which also claimed a February attack targeting troops in Ankara that killed 29 people, has ties to the PKK, which took up arms against the state in pursuit of autonomy for the Kurdish minority in 1984.

The conflict has claimed some 40,000 lives so far.