Assailants have set off explosives and opened fire in an attack on the premises of Turkish state-run aerospace and defence company TUSAS, killing five people and wounding more than a dozen, the interior minister said.
Two of the attackers – a man and a woman – were also killed, Ali Yerlikaya said.
He added that the militant Kurdistan Workers’ Party (PKK) is suspected of being behind the attack but warned that the process of identifying the assailants continued.
Defence minister Yasar Guler also pointed the finger at the PKK, saying: “We give these PKK scoundrels the punishment they deserve every time. But they never come to their senses. We will pursue them until the last terrorist is eliminated.”
The so-called Islamic State group and leftist extremists have also carried out past attacks in Turkey.
“I condemn this heinous terrorist attack,” President Recep Tayyip Erdogan said during a meeting with Russian leader Vladimir Putin on the sidelines of a meeting in Russia.
Mr Putin offered condolences, and a US embassy statement said Washington “strongly condemns today’s terrorist attack”.
The defence ministry later said Turkish jets had struck Kurdish militant targets in Iraq and Syria after the attack, adding that more than 30 targets were “destroyed”.
TUSAS designs, manufactures and assembles civilian and military aircraft, unmanned aerial vehicles (UAVs) and other defence industry and space systems. Its UAVs have been instrumental in Turkey gaining an upper hand in its fight against Kurdish militants on its own territory and across the border in Iraq.
The attack occurred a day after the leader of Turkey’s far-right nationalist party, which is allied with Mr Erdogan, raised the possibility that the PKK’s imprisoned leader could be granted parole if he renounces violence and disbands his organisation.
Abdullah Ocalan’s group has been fighting for autonomy in south-east 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.
The country’s pro-Kurdish political party, which also condemned the attack, noted that it had occurred at a time when the possibility of a dialogue to end the conflict had emerged.
Turkish media said the assailants arrived 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.
One of the victims was identified as mechanical engineer Zahide Guclu, who had gone to the entrance to collect flowers sent by her husband, the state-run Anadolu Agency.
The taxi driver was also killed by the assailants and his body was found in the trunk of the vehicle, the agency reported.
An unidentified TUSAS employee shouted “We will work harder and produce more in defiance of the traitors” as he and other colleagues were being evacuated from the premises, according to a video aired by HaberTurk.
Security camera images, aired on television, showed a man in plain clothes carrying a backpack and holding an assault rifle.
The interior minister said security teams were dispatched as soon as the attack started at around 3.30pm.
Multiple gunshots were heard after security forces entered the site, the DHA news agency and other media reported. Helicopters were flying above the premises.
Authorities issued a temporary blackout on the coverage of the attack and halted access to social media websites.
Vice president Cevdet Yilmaz said the target of the attack was Turkey’s “success in the defence industry”.
UN secretary-general Antonio Guterres condemned the terrorist attack, saying the United Nations “stands in solidarity” with the people and government of Turkey, according to UN deputy spokesman Farhan Haq.
