Police are investigating footage that appears to show the moment a gunman shot a journalist dead during riots in Derry.

Investigators said 29-year-old Lyra McKee, who was standing next to a police vehicle, was shot accidentally by a dissident republican aiming at officers.

Footage shared by a member of the public on social media appeared to show a gunman firing at least two shots from behind a wall.

The man, dressed in dark clothing and with his head and face covered, could be seen leaning around the barrier surrounding the Creggan Day Centre to aim towards police.

He fired two shots, three seconds apart, with what appeared to be a handgun before screaming could be heard.

Violence erupts in Northern Ireland as journalist killed during riots Show all 21 1 /21 Violence erupts in Northern Ireland as journalist killed during riots Violence erupts in Northern Ireland as journalist killed during riots A burning car in Creggan, Derry after petrol bombs were thrown at police during riots in Northern Ireland PA Violence erupts in Northern Ireland as journalist killed during riots Armed police at the scene of unrest PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs being thrown at police PA Violence erupts in Northern Ireland as journalist killed during riots Belfast Journalist Lyra McKee was killed during the riots. Police Service of Northern Ireland said that McKee was allegedly shot while reporting on clashes with dissident republican rioters EPA Violence erupts in Northern Ireland as journalist killed during riots A burning car in Creggan, Londonderry after petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs are thrown at police in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Heavilly armed police guard a crime scene during unrest in the Creggan area of Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. See PA story . Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Hijacked vehicles on fire in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots hijacked vehicles one fire in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs are thrown at police in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs are thrown at police in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots A hijacked car explodes after being set on fire in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots A PSNI officer conducts a search after shots where reportedly fired in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots The scene of unrest in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Police conduct a crime scene search after shots where fired in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots The scene on Fanad Drive the following day PA Violence erupts in Northern Ireland as journalist killed during riots The scene on Fanad Drive in Londonderry, Northern Ireland, following the death of 29-year-old journalist Lyra McKee who was shot and killed when guns were fired and petrol bombs were thrown in what police are treating as a "terrorist incident". PRESS ASSOCIATION Photo. Picture date: Friday April 19, 2019. See PA story ULSTER Unrest. Photo credit should read: Brian Lawless/PA Wire Brian Lawless PA

The suspect then left and accomplices could be seen crouching to the ground where the gunman stood, potentially to pick up any evidence.

The Independent understands police are investigating the footage, as they hunt several suspects.

The gunman and three accomplices, who were also wearing dark clothing, hoods and face coverings, bear a striking similarity to men photographed launching missiles at police shortly before the shooting.

One photo showed four men throwing petrol bombs towards police vehicles, metres away from the gunman’s position.

Like the gunman and his accomplices, one man was wearing black trainers and blue gloves, another was wearing white trainers, navy joggers with a bright logo and black gloves, and the other two were wearing dark clothing.

Images showed several local residents standing behind the attackers, with some filming on their phones.

The Police Service of Northern Ireland (PSNI) are appealing for witnesses to contact them and send in any photos and videos as the investigation continues.

Deputy chief constable Stephen Martin said police were looking for multiple suspects.

Four men throwing petrol bombs and missiles at police, shortly before a shooting in Derry on Thursday (PA) (Niall Carson/PA Wire)

“We certainly believe there was more than one person who was involved in this last night,” he told a press conference on Friday. “Obviously only one person pulled the trigger but there was more than one person.

“There was certainly more than one person involved in the murder.”

Mr Martin said the murder was particularly “cruel” coming 21 years after the Good Friday peace agreement was signed.

“This will have achieved nothing,” he said, hailing Ms McKee’s work shining a light on sectarianism.

“There are people in this city who will know people they love are involved in organisations like the New IRA. I would urge those people to have conversations … in Lyra’s memory.”

Violence had broken out after the PSNI launched a major security operation in Creggan on Thursday evening.

Officers said they were aiming to disrupt dissident republicans ahead of this weekend’s commemoration of Irish independence, and searching for guns and explosives.

Police said more than 50 petrol bombs were thrown at officers, as well as fireworks and bricks, and vehicles were hijacked and set on fire.

By the time of the shooting at 11pm, there were an estimated 100 people on the streets in the area.

Assistant chief constable Mark Hamilton said: “We believe this to be a terrorist act, we believe it has been carried out by violent dissident republicans.

Woman shot dead in Londonderry unrest

“Our assessment at this time would be that the New IRA are most likely to be the ones behind this and that forms our primary line of inquiry.”

But Saoradh, a dissident republican group that has denied links to the IRA, issued a statement claiming a “Republican volunteer” had opened fire while “attempting to defend people from the PSNI/RUC”.

“Tragically a young journalist covering the events, Lyra McKee, was killed accidentally while standing behind armed crown force personnel and armoured vehicles,” a statement said.

“This outcome is heartbreaking and we extend our sincerest sympathy to the family, friends and loved ones of the deceased.”

The mayor of Derry, John Boyle, said it was “an extremely sad day”.

He said: “The citizens of Derry, or Londonderry, it doesn’t matter what you call this city, everyone is united with one voice today to speak out in the first instance, and to offer our condolences, especially to Lyra McKee’s family in Belfast, for the tragedy that occurred here in our city last night.

“You will see behind me many of our civic and political leaders. They have come here to join together with one voice to say that these events did not happen in the name of the people of this city.”

Theresa May on Friday said: “The death of Lyra McKee in last night’s suspected terrorist incident in Londonderry is shocking and truly senseless.

“My deepest condolences go to her family, friends and colleagues. She was a journalist who died doing her job with great courage.”

A book of condolence was opened at Derry’s Guildhall, where a vigil was planned on Friday afternoon, and more than £27,000 has so far been raised for her family.