A Kurdish rebel suicide bomber detonated an explosives-laden vehicle outside a police headquarters near Turkey's border with Syria, killing at least three people and wounding some 30 others, the prime minister said.
Speaking in Istanbul, Prime Minister Binali Yildirim said the victims of the attack in the town of Midyat, in Mardin province, were a police officer and two civilians. It was not clear if the toll included the suicide bomber.
The explosion occurred on a busy main street lined with cafes, shops and banks. Television images from the scene showed thick smoke rising from the site of the attack, which destroyed the facade of the police headquarters building.
In televised remarks, Mr Yildirim said the attack was carried out by the outlawed rebel Kurdistan Workers' Party, or PKK. He said concrete barriers and other security measures in place at the police headquarters had prevented a greater loss of life.
The Dogan news agency said the attack was suicide car bombing carried out with a van laden with a half-ton of explosives.
The attack came a day after a car bomb hit a police vehicle in Istanbul, killing 11 people during the morning rush hour. No one has yet claimed responsibility for the attack.
Turkey has been hit by a series of attacks in the past year. PKK rebels have targeted police and military personnel since July, when a fragile peace process between the rebels and the government collapsed.
The Islamic State group has also been blamed for a series of deadly bombings in Turkey, which is part of the US-led coalition against IS.
Mardin, where government forces are battling Kurkish militants, has endured similar attacks in the past months.
In May, three people were killed in a car bombing by Kurdish rebels against a gendarmerie station in Midyat.
In April, a soldier was killed and six others were wounded in a car bomb attack against their outpost in Mardin.