Car bomb rocks Turkish capital

A suspected suicide car bomb blast struck the crowded heart of Ankara on Sunday evening, strewing debris and setting a bus and cars on fire as emergency services responded.

Health Minister Mehmet Muezzinoglu said 37 people were killed, with 15 others seriously wounded. Some 125 were injured overall, with 71 still being treated in hospital.

The explosion occured near a bus stop in Ankara's Kizilay district. CNN Turk said witnesses described a car exploding as it hit a bus, killing and wounding people in the vicinity.

It is so far unclear who carried out the attack, but Turkey has been the target of Kurdish militants, the "Islamic State" (IS) and the far-left DHKP-C. No group has claimed responsibilty.

Turkish Interior Minister Efkan Ala said the results of the investigation would be announced tomorrow. Security officials told Reuters the initial assessment was that the Kurdistan Workers' Party (PKK) were behind the attack.

The PKK has traditionally targeted military targets. A brazen attack on civilians in the heart of the capital would signal a significant change in tactics.

The pro-Kurdish Peoples' Democratic Party (HDP) condemned the attack. The condemnation is significant because the party, which is viewed as close to the PKK, has been criticized for not speaking out against the militant Kurdish group's violence.

As with previous attacks, the government issued a gag order on reporting and news broadcasts. Some users of social media reported difficulty accessing Twitter and Facebook before a court order banned the use of the social media sites after videos and pictures of the attack went viral.

The attack comes two days after the US embassy warned of a potential terrorist attack in Ankara.

Turkey has been hit by a series of bombing attacks as fighting escalates with the PKK following the breakdown of a ceasefire last year and the NATO member experiences blowback from the war in neighboring Syria.

In February, Kurdish militants carried out a bomb attack targeting a bus carrying military personnel, killing 29 people. The bombing was claimed by TAK, an offshoot faction of the PKK, in retaliation for ongoing military operations.

In January, a suspected 'IS' suicide bomber blew himself up in Istanbul's historic Sultanahmet district, killing 11 German tourists.

More than 100 people were killed in twin suicide bombings carried out by 'IS' on a pro-Kurdish peace rally in Ankara in October.

That bombing was preceeded in July by another 'IS' bombing in the town of Suruc that killed 34 protestors.

The deteriorating security situation - especially attacks in the capital - is likely to raise pressure on the MIT intelligence agency and the ruling AKP government for failing to prevent what are increasingly becoming regular attacks.

cw/rc (AP, dpa)