A banned Kurdish militant group on Friday claimed responsibility for an attack on the headquarters of a major defense company in Ankara that killed at least five people.

A statement from the military wing of the Kurdistan Workers’ Party, or PKK, said Wednesday’s attack on aerospace and defense company TUSAS was carried out by two members of its so-called “Immortal Battalion” in response to Turkish “massacres” and other actions in the Kurdish regions.

A man and a woman stormed the TUSAS premises on the outskirts of Ankara, the Turkish capital, setting off explosives and opening fire. Four TUSAS employees were killed. The attackers arrived on the scene in a taxi which they had commandeered by killing its driver. More than 20 people were injured.

The attacker committed suicide by detonating an explosive device after being injured in an exchange of fire at the entrance to the complex, Interior Minister Ali Yerlikaya said. The attacker threw hand grenades at approaching security forces, then also blew himself up in the toilets of a nearby building, “realizing there was no way out”, said the minister.

Turkey blamed the attack on the PKK and immediately launched a series of airstrikes on locations and facilities suspected of being used by the militant group in northern Iraq or its affiliates in northern Syria .

The attack on TUSAS came at a time of growing signs of a possible new attempt at dialogue to end the more than four-decade-old conflict between the PKK and the Turkish army.

Earlier this week, the leader of Turkey’s far-right nationalist party allied with President Recep Tayyip Erdogan raised the possibility that Abdullah Öcalan, the imprisoned PKK leader, could be paroled if he renounces violence and dissolved his organization.

Öcalan, who is serving a life sentence on a prison island off the coast of Istanbul, said in a message through his nephew on Thursday that he was ready to work for peace.

The PKK’s military wing, the People’s Defense Center, however, said Wednesday’s attack was not linked to the latest “political agenda”, insisting it had been planned for a long time.

He said TUSAS was chosen as a target because weapons produced there “have killed thousands of civilians, including children and women, in Kurdistan.”

TUSAS designs, manufactures and assembles civil and military aircraft, unmanned aerial vehicles and other industrial defense and space systems. Its products have been seen as key to Turkey gaining the upper hand in its fight against Kurdish militants.

On Friday, an Iraqi security official said Turkish military aircraft had intensified strikes on sites controlled by the PKK and other loyal forces in Iraq’s northern Sinjar district. The intensive shelling targeted tunnels, headquarters and military points of the PKK and Sinjar protection units inside the Sinjar Mountains region.

A local official and a security official said the bombings killed five Yazidis. The officials spoke on condition of anonymity, in accordance with regulations.

Turkish police arrested 176 suspected PKK members in operations across Turkey on Friday, the Interior Ministry said.

Police also arrested a man who threw stones at the entrance to the headquarters of the pro-Kurdish Party for People’s Equality and Democracy, or DEM, Anadolu reported. DEM spokesperson Aysegul Dogan told media platform X that the front door and windows were broken during the attack.

The PKK is fighting for autonomy in southeastern Turkey, in a conflict that has left tens of thousands dead since the 1980s. It is considered a terrorist group by Turkey and its Western allies.

Abdul-Zahra writes for the Associated Press. AP Writer Suzan Fraser in Ankara, Turkey, contributed to this report.