• Video report by ITV News Correspondent Sally Lockwood

At first glance the Reina club looks like any other deserted nightclub after New Year's celebrations with its confetti-lined floor and empty drinks filling the bar.

But closer inspection shows the bullet marks on tables and seated cushions and the poignant high-heeled shoe left on the outside decking.

It is three days since a gunman opened fire on hundreds of partygoers at the Istanbul nightclub in the early hours of New Year's Day.

An estimated 600 people were celebrating inside the plush club in the Turkish city's Ortakoy district.

Armed with a long-barreled weapon, the gunman killed 39 and injured around 70 people before fleeing. He remains at large.

The Islamic State group has claimed responsibility for the attack.

Festive decorations still hang from the ceiling inside the Reina club, which overlooks the stunning waterfront of the Bosphorus - one of the city's most celebrated tourist spots.

The bar's mirror and windows still carry the frosted writing celebrating the arrival of 2017.

Festive decorations hang from the ceiling as friends of the club rallied around the owner. Credit: ITV News

The lone attacker had shot dead a police officer and a civilian before entering the exclusive club at 1.30am local time on Sunday.

He opened fire with an automatic rifle, reloading his weapon half a dozen times and shooting the wounded as they lay on the ground.

Bullet marks punctured the cushions at the club where hundreds of revellers had welcomed in the new year. Credit: ITV News
Tables showed the impact of the shooting after the gunman opened fire with an automatic weapon. Credit: ITV News
A high-heeled shoe remained on the outside decking. Credit: ITV News

The Haberturk newspaper quoted a barman at the club as saying the gunman had thrown explosive devices several times during the shootingspree.

The explosions were apparently aimed at disorientating people and giving himself time to reload.

Claiming the attack on Monday, Islamic State said the shooting was revenge for Turkish military involvement in Syria.

Islamic State has claimed responsibility for the lone gunman's attack on the nightclub. Credit: ITV News
The decking overlooks the stunning waterfront of the Bosphorus, one of Istanbul's main tourist spots. Credit: ITV News