Two police officers were killed and 22 others injured in an explosion near the police headquarters in the Turkish city of Gaziantep on May 1.
The office of Gaziantep regional governor Ali Yerlikaya said in a statement that the explosion was caused by a car bomb but did not say which group was behind it.
NTV television said there were sounds of gunfire as clashes erupted with the security forces.
Television footage showed chaotic scenes as ambulances rushed to help the injured lying on the ground.
The blast was heard kilometers away.
The southern city of Gaziantep borders Islamic State-controlled territory in Syria and is an important center for refugees who have fled Syria.
Based on reporting by Reuters, AP, and AFP