At least eight people have been killed and dozens wounded, including police officers, after a car bomb exploded close to a police station in the southeastern Turkish city of Gaziantep.
The powerful blast set fire to several vehicles, including a city bus carrying three of the victims, the city's mayor told Turkey's NTV news channel.
Erdal Ata, Gaziantep's governor, said: "Unfortunately we lost eight citizens and nearly 60 people are getting treated at several hospitals according to our initial information."
Al Jazeera's Sue Turton, reporting from Gaziantep, said that the death toll was likely to rise.
"We are being told that eight people have been killed and at least 57 others injured with six people in a critical condition," she said.
"Police say they have CCTV footage of a man running away from the scene just before the blast, and they are looking into it."
There was no immediate claim of responsibility but, "Kurdish militants are believed to be behind the attack," a security source told the Reuters news agency.
Turton said: "There are a lot of people here chanting anti-PKK [Kurdish Workers Party] slogans. though it is not clear if they are responsible."
"People here are scratching the heads because even if some towns are vulnerable to the PKK, this town is certainly not one of them.
"With its proximity to Syria, there is speculation that this violence is spilling out of Syria."
Omer Celik, deputy chairman of the ruling AK Party, also blamed the PKK for the attacks and called for calm.
"The PKK ... is trying to provoke our citizens by targeting the civilian population directly," Celik wrote in his Twitter account. "Our citizens must remain cool-headed."
The attack comes amid intensified fighting between the Kurdish fighters and Turkish troops in the volatile southeast region, where the PKK launched a battle for autonomy 28 years ago.
In a separate incident on Monday, in the southeast province of Hakkari, bordering Iraq and Iran, two soldiers were killed when a landmine detonated through remote control by PKK fighters blew up, authorities said.
Ankara launched an all-out offensive last month against the PKK after a series of assaults against troops in the southeast.
At least 115 fighters have been killed since the offensive began on July 23, Turkish authorities said, but PKK-related incidents appear to have intensified since then.
Gaziantep is situated near the Syrian border, where Turkey has opened a centre to receive international aid for Syrian refugees fleeing the uprising against President Bashar al-Assad.
Turkey initially cultivated good relations with Assad's administration but relations have deteriorated sharply since the Syrian uprising began.
Turkey suspects a major Syrian Kurdish movement, the Democratic Union Party (PYD), of having links with the PKK.
Turkish analysts believe Assad let the PYD take control of security of some towns in northern Syria to prevent locals from joining the rebel Free Syrian Army.
Ankara believes fighters from the PKK, designated a terrorist group by Turkey, the US and European Union, are receiving arms from Syrian forces, Reuters said.