ISTANBUL: At least four people including a suicide bomber were killed and 39 wounded in an attack on a major shopping and tourist district in central Istanbul on Saturday.

No group has yet claimed responsibility for the blast, which killed three Israelis and an Iranian.

Of the 39 people wounded in the attack, 24 were foreigners. By Sunday morning, 19 people were still being treated in hospital, eight of whom were in critical condition, the health ministry said.

The three Israeli victims, two of whom also held United States (US) citizenship, were part of a group which was on a gastronomic tour of Turkey, Israeli media said.

The fourth suicide bombing in Turkey this year hit part of Istiklal Street, a long pedestrian zone lined with global brand name shops and foreign consulates, just a few hundred metres from an area where police buses are usually parked.

Preliminary findings indicate that the outlawed Kurdistan Workers Party (PKK) or an affiliate carried out the attack, a senior Turkish official told Reuters.

“The attacker detonated the bomb before reaching the targeted point because they were scared of the police,” the official said, adding the bomber had planned to hit a more crowded spot.

Armed police sealed off the shopping street where half a dozen ambulances had gathered. Forensic teams in white suits scoured the area for evidence. Police helicopters buzzed overhead and panicked shoppers fled the area, ducking down narrow sidestreets.

“My local shopkeeper told me someone had blown himself up and I walked towards the end of the street,” one neighbourhood resident told Reuters.

“I saw a body on the street. No one was treating him but then I saw someone who appeared to be a regular citizen trying to do something to the body. That was enough for me and I turned and went back.”

Istiklal Street, usually thronged with shoppers on weekends, was quieter than normal before the blast as more people are staying home after a series of deadly bombings.

Health Minister Mehmet Muezzinoglu confirmed that 36 people had been wounded and seven of those were in serious condition. Twelve of the wounded were foreigners, he said. Israel's foreign ministry confirmed some of its citizens were among the wounded.

“We as a nation are unfortunately now face to face with a situation of unlimited, immeasurable acts that are inhumane, defy human values and are treacherous,” Muezzinoglu said.

Deadly Bombings

A suicide car bombing in the capital Ankara killed 37 people this month. A similar bombing in Ankara last month killed 29 people. A Kurdish militant group has claimed responsibility for both of those bombings.

In January, a suicide bomber killed around 10 people, most of them German tourists, in Istanbul's historic heart, an attack the government blamed on the militant Islamic State group.

Nato member Turkey faces multiple security threats. As part of a US-led coalition, it is fighting Islamic State in neighbouring Syria and Iraq. It is also battling PKK militants in its southeast, where a two-and-a-half-year ceasefire collapsed last July, triggering the worst violence since the 1990s.

In its armed campaign in Turkey, the PKK has historically struck directly at the security forces and says that it does not target civilians. However, the recent bombings suggest it could be moving toward a tactical shift. A claim of direct responsibility for Saturday’s attack could underscore that.

The PKK is looking to carry out attacks aggressively during the coming Newroz spring holiday, the official said. Newroz, which falls on March 21, is Kurdish New Year.

Turkish Foreign Minister Mevlut Cavusoglu said that the country's fight against terrorism would continue with full force. Cavusoglu made the comment at a joint news conference in Istanbul with his Iranian counterpart, who is on an official visit to Turkey.