Dominique Soguel ?and Suzan Fraser

ISTANBUL: As the death toll from the Istanbul airport attack rose Thursday to 44, a senior Turkish official said the three suicide bombers who carried it out were from Russia, Uzbekistan and Kyrgyzstan, and Turkish police raided Istanbul neighborhoods for suspects linked to the Islamic State group.

Turkish authorities say all information suggests the Tuesday night attack on Ataturk Airport, one of the world’s busiest, was the work of IS, which boasted this week of having cells in Turkey, among other countries.

Police raided 16 locations in three neighborhoods on both the Asian and European sides of the city that sprawls across the Bosporus Strait, rounding up 13 people suspected of having links to IS.

There was no immediate claim of responsibility by the militant group, which has used Turkey to establish itself in neighboring Syria and Iraq. IS has repeatedly threatened Turkey in its propaganda, and the NATO member has blamed IS for several major bombings in the past year in both Ankara and Istanbul.

Across Istanbul and beyond, funerals were held for the airport victims Thursday, and heartbroken families sobbed as they bid their loved ones farewell, including several local airport workers.

Nilsu Ozmeric wept over the coffin of her fiance, Jusuf Haznedaroglu, a 32-year-old airport worker who was fatally wounded while waiting for a bus to go home.

“The wedding was next week,” sobbed his mother, Cervinye Haznedaroglu, as visitors offered condolences.

A video obtained by the Turkish newspaper Haberturk purported to show a police officer asking one of the suicide bombers for identification before he was subsequently shot by the attacker.

A Turkish senior official, who spoke on condition of anonymity because government regulations did not authorize him to talk to the media, said the attackers were from Russia and the Central Asian nations of Uzbekistan and Kyrgyzstan.

A medical team was working around the clock to identify the suicide attackers, the official said, noting their bodies had suffered extensive damage.

Kyrgyzstan’s Foreign Ministry denied that an attacker came from that country.

Asked about the possible involvement of a Russian in the attacks, Kremlin spokesman Dmitry Peskov said he had no information on that and there was no comment either from Uzbekistan.

Russian President Vladimir Putin has said between 5,000 and 7,000 people from Russia and other nations of the former Soviet Union have joined the Islamic State group in Syria and Iraq. People from Chechnya and other provinces in Russia’s volatile North Caucasus region have had a visible presence among Islamic State fighters.

Turkish state media said the death toll in the attack rose to 44 after a 25-year-old airport worker succumbed to his wounds.

Turkey’s interior minister said the explosives used were a mix of RDX, TNT and PETN that were “manufactured.” That combination is military-grade, raising the question of how the attackers obtained the bombs, said Jimmie Oxley, a chemist and explosives expert at the University of Rhode Island.