- Revolutionary People's Liberation Front have taken prosecutor hostage
- Posted images of man with gun pointed at his head on Facebook page
- Demanded police confess to killing 15-year-old Berkin Elvan in next hour
- Elvan died after being hit on the head by a tear-gas canister during anti-government protests in Istanbul
A far-left Turkish group has taken an Istanbul prosecutor hostage and threatened to kill him within the hour unless police confess to killing a teenage boy.
The Revolutionary People's Liberation Party-Front published disturbing photographs of terrified prosecutor Mehmet Selim Kiraz with a gun to his head on their official Facebook page.
The deadline passed at 3.36pm local time (12.35pm GMT) and two gunshots were heard.
The prosecutor is leading an investigation into the death of 15-year-old Berkin Elvan who was severely wounded after being hit on the head by a tear-gas canister fired by a police officer during anti-government protests in Istanbul in June 2013.
After spending 269 days in a coma, Elvan eventually died on March 11 last year.
Threat: The Revolutionary People's Liberation Party-Front published disturbing photographs of the terrified prosecutor with a gun to his head on their official Facebook page
Horror: The prosecutor is leading an investigation into the death of 15-year-old Berkin Elvan
Television footage showed special forces officers entering the building and courthouse officials being escorted out.
Gunfire was subsequently heard at the Istanbul courthouse where prosecutor Kiraz was working, the Dogan news agency reported said.
In a statement published by Turkish media, the hostage taking was claimed by the Marxist Revolutionary People's Liberation Party-Front, which has been behind a string of recent attacks.
The group published pictures showing one of the militants - his face concealed by a scarf with the group's red and yellow insignia - holding a gun to Kiraz's head.
They had also plastered their flags and posters on the walls of his office.
Turkish media said that the group had given a deadline of 3:36 pm (13.36 BST) for the prosecutor to identify the police officers who they say were behind the killing of Elvan or he would be shot.
Prime Minister Ahmet Davutoglu met with the current and former interior and justice ministers at the ruling AK Party headquarters in Ankara to discuss the hostage taking, officials in his office said.
The DHKP-C said on its website it wanted the police officer it blames for Elvan's death to 'confess' on television, the officers involved to be tried in 'people's courts', and charges against those who attended protests for Elvan to be dropped.
Innocent: Berkin was on his way to buy bread during anti-government street protests when he was struck in the head by a high-velocity gas canister
Strength of feeling: Elvan has since become an icon for the Turkish far-left and his supporters accuse the authorities of covering up the circumstances and perpetrators of his death
The DHKP-C blames the ruling AK Party for the killing of 15-year-old Elvan, who died last March after nine months in a coma from a head wound sustained in anti-government protests.
Elvan succumbed to injuries sustained when he was hit by a tear gas canister fired by police in the mass protests of early summer 2013 against the government of President Recep Tayyip Erdogan who was then premier.
He was aged 15 at the time of his death, which was followed by mass nationwide protests that were also largely put down by the police.
Elvan has since become an icon for the Turkish far-left and his supporters accuse the authorities of covering up the circumstances and perpetrators of his death.
The United States, European Union and Turkey list the DHKP-C as a terrorist organisation. It was behind a suicide bombing at the U.S. Embassy in 2013.
In 2001, two policemen and an Australian tourist died in a DHKP-C attack in central Istanbul.