Four people were killed and three others were injured after an automatic gun mounted on an armored vehicle's turret went off in southeastern Hakkari province's Yüksekova district on Saturday, Turkish officials said.
A statement by the local governor's office said that the gunfire came from an armored police vehicle and the officer in the vehicle's gun turret was detained by colleagues. The statement cited the officer as saying the gun had gone off without him touching the trigger.
The police officer in charge of the gun was arrested on Sunday.
The bullets fired from the gun hit a furniture store under an apartment building located in town center, killing four people and injuring three others.
One of the people killed in the incident was later identified as 16-year-old Serhat Buldan, who is the nephew of Savaş Buldan, the deceased husband of Peoples' Democratic Party (HDP) deputy parliament speaker and Istanbul lawmaker Pervin Buldan. Savaş Buldan was one of the prominent victims of Turkey's "unidentified murders" in 1990's.
Interior Minister Süleyman Soylu said an investigation was launched immediately and a chief civil inspector has been appointed to lead the investigation into the incident.