ANKARA, Turkey — Attackers set off explosives and opened fire Wednesday at Turkey’s state-run aerospace and defense company TUSAS, killing four people and wounding more than a dozen, President Recep Tayyip Erdogan said.

Two of the attackers — a man and a woman — were also killed, Interior Minister Ali Yerlikaya said. He did not say what organization was behind the attack, as the process of identifying the assailants continued. Kurdish militants, the Islamic State group and leftist extremists have carried out past attacks in Turkey.

“We have four martyrs. We have 14 wounded. I condemn this heinous terrorist attack,” Erdogan said during a meeting with Russian President Vladimir Putin on the sidelines of a BRICS meeting in Russia.

Putin offered condolences. A U.S. Embassy statement said Washington “strongly condemns today’s terrorist attack.”

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TUSAS designs, manufactures and assembles civilian and military aircraft, unmanned aerial vehicles and other defense industry and space systems. Its UAVs have been instrumental in Turkey gaining an upper hand in its fight against Kurdish militants in Turkey and across the border in Iraq.

The attack occurred a day after the leader of Turkey’s far-right nationalist party that’s allied with Erdogan raised the possibility that the imprisoned leader of the outlawed Kurdistan Workers’ Party, or PKK, could be granted parole if he renounces violence and disbands his organization.

Abdullah Ocalan’s group has been fighting for autonomy in southeast Turkey in a conflict that has killed tens of thousands of people since the 1980s. It is considered a terrorist group by Turkey and its Western allies.

Turkish media said three assailants arrived Wednesday at an entry to the TUSAS complex in a taxi. The assailants, carrying assault weapons, detonated an explosive device next to the taxi, causing panic and allowing them to enter.

The taxi driver was among the dead, according to HaberTurk television.

Security camera images, aired on television, showed a man in plainclothes carrying a backpack and holding an assault rifle.

The interior minister said security teams were dispatched as soon as the attack started at around 3:30 p.m.

Multiple gunshots were heard after security forces entered the site, the DHA news agency and other media reported. Helicopters were seen flying above the premises.

Vice President Cevdet Yilmaz said the target of the attack was Turkey’s “success in the defense industry.”