Four individuals were killed and 14 were injured in an attack on the headquarters of a leading Turkish defense company near Ankara, as confirmed by Turkish authorities on Wednesday.

President Recep Tayyip Erdogan was in Russia for discussions with Russian President Vladimir Putin  at the time of the attack, and condemned the assault at the state-run Turkish Aerospace Industries (TAI) as a “terrorist attack.”

At their summit in Kazan, Putin expressed his condolences over the attack.

Interior Minister Ali Yerlikaya reported that the two attackers, “a woman and a man, had been neutralized” and that three of the injured were critically wounded.

Local media broadcast shows a video with clouds of smoke and flames at the site in Kahramankazan, a small town located about 25 miles north of Ankara.

Turkey’s defense ministry later reported that in response, it had launched strikes against on Kurdistan Workers Party (PKK) in Northern Iraq and northern Syria, according to Reuters.

For many years, Turkey has battled Kurdish rebels within its southern regions and have conducted numerous cross-border operations against the PKK and its ally, the YPG, in northern Iraq and Syria.

Media outlets which had been showing live video from the scene were forced to stop their broadcasts after Turkey’s media watchdog ordered a blackout of images from the site.

According to Haberturk TV, d there was an ongoing “hostage situation,” without providing no further details.

Meanwhile, NTV, a private television network, reported hearing gunfire following an initial explosion around 4 p.m. local time (8 a.m. Eastern Time).