The Kurdistan Freedom Falcons, or TAK, said two of its members had sacrificed their lives in the Saturday night attack that targeted security forces outside the Besiktas stadium shortly after the conclusion of a match.
"Two of our comrades were heroically martyred in the attack," according to a statement posted on TAK's website. It described the blasts as reprisal for state violence in the southeast and the ongoing imprisonment of Abdullah Ocalan, the leader of the Kurdistan Workers' Party, or PKK. TAK is considered by authorities as a PKK offshoot.
The twin car-and-suicide bombings near the stadium enraged top officials, including President Recep Tayyip Erdogan, who vowed to hunt down the perpetrators. The attack was the latest large-scale assault to traumatize a nation confronting an array of security threats.
Turkey is a NATO member and a partner in the U.S.-led war against the Islamic State group. The attack targeted police officers, killing 30 of them along with seven civilians and an unidentified person, Turkish Interior Minister Suleyman Soylu told reporters. He said 13 people had been arrested in connection with the "terrorist" act.
In an address at a funeral for the slain police officers before TAK's statement was released, a furious Soylu condemned Kurdish rebels and their allies in the West, referring to the PKK as "animals." "Have you accomplished anything beyond being the servants, pawns and hit men of certain dark forces, of your dark Western partners?" he asked.
Turkish officials didn't make any further comments after the TAK claim of responsibility was posted. The battle between the PKK and the Turkish state has resulted in the deaths of tens of thousands of citizens. Turkish officials frequently accuse the West of supporting the Kurdish insurgency and of interfering in Ankara's fight against the militants.
Erdogan vowed his country would fight "the curse of terrorism till the end" after paying a visit to some of the wounded at Haseki Hospital in Istanbul. Hundreds of flag-carrying demonstrators marched along Istanbul's coastline toward the stadium at the heart of the blast area. Flags flew at half-staff across the country and at Turkey's foreign missions. Passers-by placed flowers on barriers surrounding the soccer stadium.
The first and larger explosion took place about 10:30 p.m. Saturday after Besiktas beat Bursaspor 2-1 in the Turkish Super League. Erdogan said the attack's timing aimed to maximize the loss of life, but most fans had left before the detonation.
Soylu said the first blast was caused by a passing vehicle that detonated in an area where police special forces were located at the stadium exit. A riot police bus appears to have been the target. Moments later, a person who had been stopped in nearby Macka Park committed suicide by triggering explosives, according to the minister.
He said 136 people remained hospitalized Sunday after the attack, including 14 in intensive care. TAK claimed the Turkish people weren't their target but warned "no one should expect a comfortable life" as long as the ruling party "continues to torture the mothers of Kurdistan every day."
Armed conflict between the Turkish state and Kurdish militants resumed in July 2015 after peace talks unraveled. While much of the violence has concentrated in the impoverished and pre-dominantly Kurdish southeast, it has also spread to other cities, including the capital, Ankara, where TAK has claimed February and March suicide bombings.
Experts have determined that up to 400 kilograms (880 pounds) of explosives were used in the car bomb, Deputy Prime Minister Numan Kurtulmus told CNN Turk. To the mournful sound of trumpets, funeral services were held at Istanbul's police headquarters for some of the slain officers. Their comrades solemnly carried the coffins, which were draped in the Turkish flag, as a sea of mourners wept around them.
Erdogan presided over a security meeting after the funeral ceremony and hospital visit. Soccer fans proved their resilience by showing up to watch a game pitting Istanbul's Galatasaray and Gaziantepspor at a different stadium.
"What happened last night was extremely saddening but they need to know that Turkish people will not yield to such things," Galatasaray supporter Erkan Duman told The Associated Press. "It's not like we will give up things, especially things we love, just because they want us to."
Turkey has witnessed a spate of IS and Kurdish-linked attacks this year. Saturday's bombings were one of the bloodiest to hit Istanbul, a city at the crossroads of Europe and Asia, until recently a popular tourist destination.
That changed after a series of IS-linked suicide bombings targeting tourists, including a sophisticated attack on the city's Ataturk Airport in June that killed 44 people and wounded scores of others. PKK-linked militants have claimed other deadly attacks in Ankara, Istanbul and areas in southeast Turkey.
A state of emergency is in force following a failed July 15 coup attempt and the resulting government crackdown on alleged coup sympathizers has landed thousands in jail and forced tens of thousands of people from their jobs. Critics call the move a witch hunt.
Cinar Kiper, Ayse Wieting and Bulut Emiroglu contributed to this report.
