A strong blast rocked Turkey's largest Kurdish-majority city of Diyarbakir on Tuesday near the riot police headquarters, just days before a key referendum on boosting President Recep Tayyip Erdogan's powers.
Turkish media is reporting one person has died and several people have been injured.
A police source said the explosion appeared to have taken place in a vehicle repair section of the police compound, causing part of the roof to collapse and wounding at least four people. The Dogan news agency said one was in a critical condition.
The blast could be heard in several areas of the southeastern city, an AFP journalist at the scene said.
Grey smoke rose from the area as ambulances rushed to the scene.
The cause of the explosion was not immediately known, but Interior Minister Suleyman Soylu told CNN Turk it occurred during the repair of a vehicle and was not the result of foul play.
Turks will on Sunday vote on whether to approve constitutional changes giving Erdogan executive presidential powers, which critics say would drag the country into one-man rule.
The explosion was in the central, largely residential district of Baglar, where a car bombing by suspected Kurdistan Workers Party (PKK) militants wounded scores of people last November.
The group is designated by Ankara, the United States and the European Union as a terror group.
Diyarbakir is the largest city in Turkey's southeast, where the PKK has fought an insurgency against the state for more than three decades to press demands for Kurdish autonomy.
The southeast has been battered by renewed fighting between Kurdish rebels and Turkish security forces since a fragile truce collapsed in summer 2015.
The outlawed Kurdistan Workers' Party (PKK) has been waging an insurgency against the Turkish state since 1984 during which over 40,000 people have been killed.
