A car bomb targeting the military in Turkey's capital has killed 28 people and injured 61, Deputy Prime Minister Numan Kurtulmus said in televised remarks Wednesday, adding that it remained unclear who was behind the attack.
Military personnel and civilians were killed in the attack, which took place in the key government district of Ankara.
The government and the military condemned the "terrorist attack" and vowed to find the culprits.
"This not an attack against our military, but on our dear nation," Kurtulmus said, calling for national unity.
The blast took place near a traffic intersection not far from an air force headquarters and in the same vicinity as the parliament. There was no immediate claim of responsibility.
Initial images broadcast on television showed a pillar of black smoke rising over the city, large flames at the scene and a bus on fire. The government then quickly imposed a partial broadcast ban, which affected unofficial information and images from the scene.
The office of Prime Minister Ahmet Davutoglu said it was investigating and the premier cancelled a planned trip to Brussels, which was meant to be timed with a European Union summit.
President Recep Tayyip Erdogan, who had convened an emergency security meeting, cancelled a visit to Azerbaijan.
Erdogan issued a statement saying Turkey's patience with terrorism was wearing thin and vowed to take action against the perpetrators of the attack. He stressed Turkey's right to self-defence.
In October, a twin suicide bombing in Ankara killed 100 people and was blamed on Islamic State. Authorities also blamed the extremist group, which operates in neighbouring Iraq and Syria, for a blast in Istanbul last month that killed 11 German tourists.
Turkish military forces in the south-east of the country are engaged in battles with the armed Kurdistan Workers' Party (PKK), and other attacks in Turkey in the past have also been blamed on banned leftist groups.
The Health Ministry said 32 ambulances were dispatched to the scene.
The attack was condemned by the United States and European Union.