Turkish news agencies say that members of a banned leftist group have taken a chief prosecutor hostage in his office inside a court house in Istanbul.

Private Dogan news agency says some shots were fired inside.

State-run Anadolu Agency and state television, TRT, identified the prosecutor as Mehmet Selim Kiraz. He is the prosecutor investigating the death of a teenager who was hit by a police gas canister fired during nationwide anti-government protests in 2013.

A website close to the left-wing DHKP-C group said that militants from the banned organization had taken the prosecutor hostage at midday and had given authorities three hours to carry out five demands, including forcing policemen held responsible for the teenager's killing to confess the death.

The group also demanded that the policemen be tried by "peoples' courts" and for court officials to drop prosecutions or investigations against people who took part in protests denouncing the boy's death. The website showed a picture of someone holding a gun to a man's head with posters from the group in the background.

Dogan said special forces' police have entered the building, which has been been evacuated. It was not clear how the assailants sneaked the arms in to the court house.