Terrorism returned to the streets of London today as two suspected Muslim fanatics butchered a man in broad daylight in the name of "Allah".
One of the attackers behind the barbaric killing, near the Royal Artillery Barracks in Woolwich, was filmed wielding a bloodied meat cleaver, saying: "We swear by almighty Allah we will never stop fighting you."
Scotland Yard's top officer tonight confirmed two men had been arrested after a man was butchered in broad daylight on the streets of London.
Metropolitan Police Commissioner Sir Bernard Hogan-Howe said officers from the counter-terrorist unit were leading the investigation into the "shocking and horrific" Woolwich murder.
"We have launched a murder investigation, being led by the Counter Terrorism Command. Two men have been arrested in connection with that murder."
Security has been stepped up at military barracks across London, as eyewitnesses and others close to the area said the victim, pronounced dead immediately, was a serving British soldier.
Metropolitan Police officers called to the terrifying scenes opened fire and shot the attackers, who were rushed to nearby hospitals, where one is said to be in a serious condition.
UK Prime Minister David Cameron described the attack as "truly shocking" while the Home Secretary Theresa May said it was "sickening and barbaric".
After it became clear through eyewitness accounts that the attackers had political and religious motives, the Government held a so-called Cobra emergency response meeting
In a chilling development, footage emerged of one of the suspected killers, apparently explaining his terrifying actions.
In the clip, obtained by ITV News, he is heard to say: "We must fight them as they fight us. An eye for an eye, a tooth for a tooth.
"I apologise that women have had to witness this today, but in our land our women have to see the same. You people will never be safe. Remove your government, they don't care about you."
The man adds: "You think David Cameron is going to get caught in the street when we start bussin' our guns? You think politicians are going to die?
"No it's going to be the average guy, like you, and your children.
"So get rid of them. Tell them to bring our troops back so you can all live in peace."
The attacker, who spoke clear English without a foreign accent, is then seen walking towards the victim, who is lying in the street. Another man is standing by a car that has collided with a road sign.
At a press conference in Paris, the Prime Minister said Britain has faced such terror attacks before and added: "We will never buckle in the face of it."
In expressing solidarity with the PM, French president Francois Hollande referred to the murdered man as a "British soldier".
The Prime Minister, who was planning to stay in Paris overnight, is to return tonight instead.
Footage and pictures show a frenzied scene at the junction of John Wilson Street and Artillery Place in Woolwich.
Some images show three men lying scattered in the street, surrounded by discarded weapons and splashes of blood.
Eyewitnesses huddled behind a police cordon as around 30 to 40 officers secured the scene, just around the corner from Mulgrave Primary School.
Woolwich and Greenwich MP Nick Raynsford said it was his understanding that the dead man was a serving soldier.
He said he had spoken to both borough commander Richard Wood and Lieutenant Colonel Bob Christopher at Woolwich Barracks.
Mr Raynsford said: ''It's been suggested it was the product of a road traffic accident, but that's pure speculation.
''I'll be talking to everyone who is involved, we will be trying to do everything possible to try and ensure calm in the area. People will be very, very shocked."
One witness, identified as James Heneghan, said he and his partner saw two black men attack a young man aged around 20-years-old in a Help for Heroes T-shirt with kitchen knives like he was ''a piece of meat''.
''They were hacking at this poor guy, literally,'' he told LBC radio. ''They were hacking at him, chopping him, cutting him.''
The Cobra meeting, which lasted around an hour, heard that security had been tightened at Woolwich barracks and increased at all London barracks, Downing Street said.
The meeting lasted just under an hour and was attended by the Home Secretary, Defence Secretary Philip Hammond, Mayor of London Boris Johnson, Met Commissioner Sir Bernard Hogan-Howe, Met Assistant Commissioner Cressida Dick and intelligence agencies.
The meeting was told there are strong indications that it was a terrorist incident.
Other leading figures came forward to express their horror and offer sympathies to the victim's families.
A Buckingham Palace spokesman said: "The Queen is of course concerned by the report of an attack in Woolwich earlier today. Her Majesty is being kept informed."
The spokesman also confirmed the Queen will visit the King's Troop Royal Horse Artillery at Woolwich barracks on May 31, which was planned before today's attack.
Ed Miliband MP, Leader of the Labour Party, said: "This is a truly appalling murder which will shock the entire country."
London Ambulance Service confirmed a man was found dead at the scene, while two other men were taken to hospital, one of them in a serious condition.
John Wilson Street was shut in both directions between Artillery Place and New Ferry Approach.
Eyewitnesses took to Twitter to recount the horrific events.
One user, using the account @Boyadee, wrote of seeing two men decapitate another man in front of him as he went to a nearby shop.
He suggested that the men looked like they were on drugs, waiting for the police to arrive and then going towards them with ''just two machete and an old rusty lookin revolver''.
''I couldn't believe my eyes. That was some movie sh*t,'' he wrote.
The Ministry of Defence said it was urgently looking at the reports that the incident involved a soldier but had no further comment.
The incident occurred some 200 yards from the Royal Artillery Barracks, adjacent to Woolwich Common, the historical home of the Royal Artillery.
The barracks, also known as the Woolwich station, now houses a number of the King's Troop Royal Horse Artillery and independent companies of the Grenadier and Coldstream Guards.
The shooting events at the 2012 Summer Olympics and Paralympics were held at a temporary venue at the Barracks.
Metropolitan Police Commander Simon Letchford confirmed tonight that the two attackers were shot by armed officers.
He said in a statement: ''A number of weapons were reportedly being used in the attack, and this included reports of a firearm."
He added: ''Two men, who we believe from early reports to have been carrying weapons, were shot by police. They were taken to separate London hospitals. They are receiving treatment for their injuries."
The Independent Police Complaints Commission (IPCC) has started an investigation in to the circumstances surrounding the shooting of the two suspects. This is a matter of routine when officers use their firearms.
Help for Heroes, the charity whose t-shirt witnesses said the victim was wearing, said: "Help for Heroes is appalled to hear that a man, believed to be a serving soldier, has been brutally murdered in Woolwich today.
"We are desperately saddened to hear of this sickening attack and offer our thoughts and prayers to his family, colleagues and friends."
Around 50 supporters of the EDL gathered at Woolwich Arsenal train station near the scene and threw bottles at police.
Officers formed a cordon and the men left the immediate area after the brief incident.
Some of the EDL supporters gathered at The Queen's Arms pub on Burrage Grove, where they sang nationalistic songs.
Riot police with shields stood guard outside for a short time, before moving back into their vans.