An offshoot of the militant Kurdistan Workers Party (PKK) claimed responsibility on Sunday for twin bombings that killed 38 people and wounded 155 outside an Istanbul soccer stadium, an attack for which the Turkish government vowed vengeance, Reuters reports.

The Kurdistan Freedom Hawks (TAK), which has claimed several other deadly attacks in Turkey this year, said in a statement on its website that it was behind Saturday night's blasts, which shook a nation still trying to recover from a failed military coup and a number of bombings this year..

Saturday's attacks took place near the Vodafone Arena, home to Istanbul's Besiktas soccer team, about two hours after a match at the stadium and appeared to target police officers.  The first was a car bomb outside the stadium, followed within a minute by a suicide bomb attack in an adjacent park.

TAK, which has claimed responsibility for an Ankara bombing that killed 37, is an offshoot of the PKK, which has carried out a violent, three-decade insurgency, mainly in Turkey's largely Kurdish southeast.

"What we must focus on is this terror burden.  Our people should have no doubt we will continue our battle against terror until the end," Turkey President Tayyip Erdogan told reporters after meeting injured victims in an Istanbul hospital.