A meat cleaver is clasped in his blood-smeared left hand, the other - stained red with human blood too - waves manically as he shouts at the camera, ranting his justification for the atrocity on the streets of southeast London.
At about the same time in the nearby Musgrave primary school, head teacher David Dixon orders a lockdown after seeing the body of a man, believed to be a young soldier, lying on John Wilson Street.
If there was any doubt why this young man, whom witnesses said was wearing a Help for Heroes military charity t-shirt and aged in his early 20s, had lost his life in such a brutal fashion, that was soon quashed. Shouting the justification of al-Qaeda-inspired jihadists across the world, the tall black man spat his words to an eyewitness filming on his mobile phone.
"We swear by almighty Allah we will never stop fighting you. The only reasons we have done this is because Muslims are dying every day. This British soldier is an eye for an eye a tooth for tooth.
"We must fight them. I apologise that women 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."
In a few minutes on a cloudy Wednesday, terror had struck again in Britain in a style counterterror officials have long feared; brutally, out of nowhere and with chilling and horrific effect.
One witness named only as James saw the whole thing unfold as he drove his girlfriend to work. His voice choking, he had to break off repeatedly as he described on LBC radio what happened. "We were coming round the corner into John Wilson Street. Slightly to the left about five feet away there was a Vauxhall crashed into a signpost. To the left of the car there was two guys with the victim on the floor.
"We thought they were helping him. But next thing my partner, she let out an almighty scream. We then saw clearly the two guys with the meat cleaver, and knives. They weren't little small knives, they were both butchers' type knives. They were hacking this poor guy literally. We saw it all. They were hacking him, we thought they were trying to remove his organs. They were digging him, cutting him. We jumped out of the car and shouted. One of the black guys got in a car, got out a black bag and pulled a handgun out and shouted: 'Get in the car.' He was waving this gun around."
As James moved his car up the road and called the police, other people gathered on the main street, some shouting for the killers to stop. A handful of incredibly brave women stood over the body of the now dead young man, shielding him, covering him, making attempts - sadly far too late - to protect him.
"While I was on the phone to the police they were still hacking away at him," James said. "They were crazed, they were animals. They dragged the body into the middle of the street and left him there."
For what witnesses said was 15 to 20 minutes - the timing has not been confirmed by the police - the men waited for the armed response teams they knew were coming. Unarmed officers were behind barriers, waiting too.
Joe Tallant, 20, a local man who said he witnessed the attack, said a friend's mother comforted the victim, who may have already been dead at that stage. He said that one of the attackers said: "No man is coming near this body."
There was little doubt that the attackers wanted witnesses for their macabre act. "They were asking people to take pictures of them. It was like they wanted to be famous or something, but in a stupid way. In the time that it took for the police to come they could have got away, but they just waited. When the cops came the attackers just walked towards them. They plodded. A lady jumped out and shot them."
As police drove in, James and other witnesses said the men charged them. There were unconfirmed reports that one of the attackers opened fire with his handgun, and then four to six shots rang out from armed police, and the men were felled by a female police marksman.
Graham Wilders said: "All I heard was four shots … These men actually went for the police with the machetes, knife and handgun. I don't think they cared. I don't think they really cared because they went for the police with a handgun."