An explosion that injured at least four people at a police compound in the southeastern Turkish city of Diyarbakir was an accident that occurred during repair work, the interior minister has said.
The April 11 blast, which sent a large plume of smoke over Diyarbakir's central Baglar district, occurred amid tension ahead of an April 16 referendum on boosting President Recep Tayyip Erdogan's powers.
Interior Minister Suleyman Soylu said no external forces had been involved in the incident in the restive city, which happened during repair work on armored vehicles at police headquarters.
One of the injured was said to be in critical condition.
The largely residential neighborhood in the predominantly Kurdish city was the site of a car bombing by suspected Kurdistan Workers Party (PKK) militants in November that wounded dozens of people.
Diyarbakir is the largest city in southeastern Turkey, where PKK militants have fought an insurgency against Turkish government forces for more than three decades to press demands for Kurdish autonomy.
Turkish voters are due on April 16 to cast ballots in a referendum that could vastly expand Erdogan's powers by transforming Turkey into a presidential republic.