A car bombing in Turkey's capital has killed at least 27 people and wounded around 75 others on Sunday, officials said.
The blast occurred on the city's main boulevard, Ataturk Bulvari, close to Ankara's main square, Kizilay. It happened adjacent to bus stops near a park.
The private NTV news channel said a car, believed to be laden with explosives, detonated close to a bus. Several vehicles then caught fire, it said. The area is close to government offices, including ministries.
Prime Minister Ahmet Davutoglu convened an emergency security meeting after the bombing, which also shattered the windows of shops that line Kizilay square.
Dogan Asik, 28, said he was on a bus when the explosion occurred.
"We were thrown further back into the bus from the force of the explosion," said Asik, who sustained injuries on his face and arm.
Police sealed off the area and pushed onlookers and journalists back, warning there could be a second bomb. Forensic teams were examining the scene.
The bombing is the third in the city in five months and comes as Turkey is faced with an array of issues, including renewed fighting with the Kurdish rebels, threats from the Islamic State group and a Syrian refugee crisis.
It occurred just three weeks after a suicide car bombing in the capital targeted buses carrying military personnel, killing 29 people. A Kurdish militant group which is an offshoot of the outlawed Kurdish rebel group, the Kurdistan Workers' Party, or PKK, claimed responsibility for the Feb. 17 attack. The government, however, said that attack was carried out by a Syrian Kurdish militia group in concert with the PKK, which has waged a 30-year insurgency.
Sunday's attack also came two days after the U.S. Embassy issued a security warning about a potential plot to attack Turkish government buildings and housing in one Ankara neighborhood and asked its citizens to avoid those areas.
As with the previous bombings, Turkish authorities quickly imposed a ban Sunday preventing media organizations from broadcasting or publishing graphic images of the blast or from the scene.
Hundreds of people have been killed in Turkey in renewed fighting following the collapse of the peace process between the government and the PKK in July. Authorities on Sunday had declared curfews in two towns in the mainly Kurdish southeast region in anticipation of large-scale military operations against PKK-linked militants.
Turkey also has been struck by several bombings in the last year that were blamed on IS as the government joined efforts led by the U.S. to fight the extremist group in Syria. The deadliest came in October when a peace rally outside Ankara's main train station killed 102 people.