Turkish jets launched air strikes inside Iraqi Kurdistan late Sunday, after a blast earlier the same day injured two police officers near the parliament building in Ankara.
In the hours following the bombing, Turkish President Recep Tayyip Erdogan had already vowed that "terrorists" would never achieve their aims.
The Kurdistan Workers' Party (PKK), listed as a terror group by Turkey and its Western allies, claimed responsibility for the blast. It has waged a deadly insurgency against Ankara for four decades.
The district targeted in the bombing is home to several other ministries and the Turkish parliament, which reopened as planned in the afternoon with an address from Erdogan.
"The villains who threaten the peace and security of citizens have not achieved their objectives and will never achieve them," Erdogan said.
The interior ministry said two attackers had arrived in a commercial vehicle around 9:30 am (0630 GMT) in front of "the entrance gate of the General Directorate of Security of our Ministry of the Interior, and carried out a bomb attack."
"One of the terrorists blew himself up," Interior Minister Ali Yerlikaya told journalists outside the ministry. "The other was killed by a bullet to the head before he had a chance to blow himself up."
Two police officers were lightly injured in the exchange of fire, but their lives were not in danger, he added.
The Ankara prosecutor's office said it had opened an investigation and banned access to the area. Local media were asked to stop broadcasting images from the scene of the attack.
In a statement to the ANF news agency, which is close to the Kurdish movement, the PKK said that "a sacrificial action was carried out against the Turkish Interior Ministry".
On Sunday evening, an official in Iraqi Kurdistan reported Turkish army planes bombing parts of the Bradost region and the village of Badran.
Turkey's defence ministry acknowledged an "air operation" in northern Iraq to "neutralise the PKK". The ministry said that "20 targets used by terrorists" had been destroyed.
In his opening remarks, Erdogan also slammed the European Union for stalling his country's membership bid, stating that Turkey "no longer expects anything from the European Union, which has kept us waiting at its door for 40 years".
"We have kept all the promises we have made to the EU but they have kept almost none of theirs," he said, adding that he would not "tolerate any new demands or conditions" for his country to join the bloc.
This session of Turkey's parliament must also validate Sweden's entry into the NATO alliance. Hungary and Turkey in July lifted their vetoes against Sweden's entry into the Atlantic alliance, but have been slow to ratify its membership.
Erdogan indicated in July that ratification by the Turkish parliament would not take place before October, but it is expected to be approved during this parliamentary year.
For months, Erdogan has been putting pressure on Sweden to take action against Koran desecrations that have strained relations between the two countries.
Sweden's prime minister Ulf Kristersson was quick to pledge in a statement that his country "once again confirms its commitment to long-term cooperation with Turkey in the fight against terrorism".
Numerous foreign leaders also voiced support for Turkey after the attack, with messages of support coming from Germany, the United Kingdom and the United States embassy in Ankara.
The Turkish capital has been the scene of several attacks, particularly during the years 2015 and 2016 -- many claimed by the PKK or the Islamic State group.
The PKK has waged an insurgency against the Turkish state since 1984 in a conflict that has claimed tens of thousands of lives.
In October 2015 an attack in front of a central station in Ankara claimed by the Islamic State group killed 109 people.
The most recent bomb attack in Turkey was in a shopping street in Istanbul in November 2022, where six were killed and 81 were injured.