CONSTANTINOPLE — A suicide car bomber set off an explosion Dec. 17 that demolished a public bus transporting off-duty soldiers in Turkey’s central province of Kayseri, killing 13 troops and wounding 56 other people, authorities said.

The blast comes a week after a car bomb attack claimed by Kurdish militants killed 44 people, mainly riot police, and wounded over 150 others near a soccer stadium in Constantinople.

Interior Minister Suleyman Soylu said the identity of the Kayseri attacker was known and that seven people had been taken into custody in connection with the attack. Police were searching for five others.

Prime Minister Binali Yildirim said the suicide bomber ambushed a commando brigade on weekend leave in the city of Kayseri.

The Turkish army said 48 troops were among the wounded in the “treacherous attack.” The state-run Anadolu Agency said the explosion at the entrance gate to Erciyes University hit a bus transporting off-duty soldiers.

Speaking in Kayseri, Health Minister Recep Akdag told reporters 56 people had been wounded in the attack, including four who were in critical condition.

Images taken moments after the explosion showed a smoking public bus, still in flames, with its windows blown open and its interior blackened.

There was no immediate claim of responsibility but the statements of top officials suggested suspicion was focused on the outlawed Kurdistan Workers’ Party, or PKK, which Ankara and the West consider a terrorist organization.

Kurdish militants have claimed multiple attacks against soldiers and police across Turkey this year in violence that has also caused many casualties among civilians.

“Turkey is under a combined attack by terrorist organizations, especially the divisive terrorist organization,” President Recep Tayyip Erdogan said in a statement, referring to the PKK.

Turkey has fought the PKK for decades in a conflict that has claimed tens of thousands of lives.

The collapse of a two-and-a-half year cease-fire in July 2015 set the stage for a violent new chapter and ushered vast security operations in Turkey’s predominantly Kurdish southeast.

Turkey is also at odds with Western-backed Kurdish factions fighting against Islamic State extremists in neighboring Syria and Iraq. Turkey views these groups as extensions of the PKK.

“We know that these attacks we have endured are not unrelated to happenings in Syria and Iraq, or even our economical fluctuations,” Erdogan said.

A state of emergency was declared following a botched July 15 coup attempt in Turkey and remains in force.

The Turkish government has detained tens of thousands of people and fired tens of thousands of others for alleged ties to a cleric-led movement it says was behind the attempted coup, a claim the group denies.

As usual with attacks in Turkey, the prime ministry office imposed a temporary blackout on coverage of the explosion and urged media to refrain from publishing anything that may cause “fear in the public, panic and disorder and which may serve the aims of terrorist organizations.”

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By DOMINIQUE SOGUEL. Ayse Wieting, Bulut Emiroglu and Neyran Elden in Constantinople also contributed reporting