Diyarbakir (Online): A strong explosion Turkey´s largest Kurdish-majority city of Diyarbakir on Tuesday near the police headquarters, just days before a key referendum on boosting President Recep Tayyip Erdogan´s powers.

According to medics, the blast could be heard in several areas of the southeastern city, at least four people were injured.

Grey smoke rose from the area as ambulances rushed to the scene.

The cause of the explosion was not immediately known.