The attack targeted a compex housing judges and prosecutors in the town of Viransehir, in Sanliurfa province, near the Syrian border.
Sanliurfa provincial governor Gungor Azim Tuna told the state news agency Anadolu that a three-year-old infant had been killed in the huge explosion.
Initial reports suggested a suspect thought to be aged between 18 to 20 parked a car loaded with explosives outside the complex.
A massive car bomb has rocked a town in southern Turkey
A terror attack was carried out as the car bomb was remotely detonated. The housing complex has been largely damaged
Gungor Azim Tuna
Mr Tuna said: ”A terror attack was carried out as the car bomb was remotely detonated. The housing complex has been largely damaged."
The blast shattered windows in several buildings nearby and was felt across the neighbourhood.
Justice Minister Bekir Bozdag described the bombing as a terrorist attack saying it targeted judges, prosecutors and clerks.
There was no immediate claim of responsibility.
The car bomb was detonated in front of a building used by judges and prosecutors
The PKK launched a separatist insurgency in 1984 in which more than 40,000 people have been killed.
The conflict flared up again in July last year after the collapse of a two-year-old ceasefire.
The PKK is designated a terrorist organisation by Turkey, the United States and the European Union. Leftist and Islamist groups have also carried out bomb attacks across Turkey in the past, with Islamic State blamed for some recent attacks.
Emergency services raced to the scene of the blast
The last attack was in early January when an offshoot of the PKK clashed with police and detonated a car bomb outside the courthouse in Aegean city of Izmir, killing a police officer and a court employee.
Turkish cities and towns have been hit by several similar attacks in the past year.
A car packed with explosives erupted into a huge fireball Turkey mourns after Istanbul nightclub attack Tue, January 3, 2017
Turkey mourns after a New Year's Day mass shooting at a packed Istanbul nightclub killed 39 people.
Play slideshow AFP/Getty Images 1 of 13
Relatives of Ayhan Arik, one of the victims of the Reina night club attack mourn during his funeral ceremony on January 1, 2017 in Istanbul.
Last May police in Viransehir, a mainly Kurdish and Arab town, shot dead four men said by officials to have been members of the outlawed Kurdistan Workers' Party (PKK).
The pro-government Yeni Safak newspaper said that they had been planning to bomb a government building.
- 'The EU funds TERROR in Middle East', rages Turkey's President Erdogan
- Kurdish protestors attacked as anti-Erdogan marches sweep Europe
- Turkish president accuses Europe of siding with terrorists