ANTI-terror police were today preparing to question the two men shot and injured after the Woolwich soldier killing as details about their backgrounds began to emerge.

Sources said both men, who are being treated in hospital, are believed to be British citizens with Nigerian connections who converted to a radical form of Islam. But they are not thought to have links to terror groups based in Nigeria, such as the jihadist organisation Boko Haram.

The news emerged as security chiefs and politicians met to discuss their response to the barbaric attack.

Arriving for a meeting of the Government's Cobra crisis commitee, mayor of London Boris Johnson said it was wrong to link the murder with British foreign policy or the actions of Britains armed forces overseas.

Mr Johnson said: "The fault lies wholly and exclusively in the warped and deluded mindset of the people who did it."

The mayor also urged Londoners to go about their lives in the normal way.

Others attending the meeting included Sir John Sawers, head of security service MI6.

Security was tight this morning at the army barracks near the scene of yesterday's killing.

The Ministry of Defence said: "As a result of the incident in Woolwich, a number of additional security measures have been put in place. As you would expect, we would not talk about the details of these measures."

But sources denied reports that military personnel had been told not to wear uniforms off base.

Prime Minister David Cameron was briefed by Metropolitan Police commissioner Sir Bernard Hogan-Howe on the murder investigation before chairing the meeting of Cobra at 10 Downing Street.

In a message on Twitter, Mr Cameron said: "I have been updated by the commissioner and will chair Cobra shortly. I will make a statement on this sickening killing this morning."

Meanwhile, a woman who risked her life to confront one of the killers who murdered the soldier in broad daylight in front of horrified passers by described how she tried to calm him moments after the barbaric attack.

Ingrid Loyau-Kennett, 48, was on a bus heading through Woolwich when she spotted the stricken soldier lying bloodied in the road.

Her bravery - and that of others who tried to reason with the killers - has been praised, particularly in the wake of amateur footage from the scene, which shows one of the killers making political statements about the slaughter while still brandishing weapons.

Cub leader Ms Loyau-Kennett, of Helston in Cornwall, told ITV Daybreak she initially thought the victim had been injured in a car crash after spotting a badly-damaged vehicle on a pavement at the scene.

She said: "I went to the guy and when I approached the body there was a lady cradling him. And then (one of the killers), the most excited one of the two, said 'Don't go too close to the body'.

"I thought, OK. And because I was down I could see a butcher's knife and an axe - that's what he had - and blood. I thought, 'what the heck?' I thought obviously he was a bit excited and the thing was just to talk to him."

Ms Loyau-Kennett said she tried to reason with the killer to focus his attention away from other potential victims, as large crowds began to gather at the scene.

She said: "I know it's big today but for me it was just a regular guy, just a bit upset. He was not on drugs, he was not drunk.

"He said 'Don't touch, I killed him'. I said 'Why?' He said 'He's a British soldier. He killed people. He killed Muslim people in Muslim countries'.

And I said, 'OK. So what would you like?' I tried to make him talk about how he felt. He said all the bombs dropping and blindly killing women, children...

"More and more people were starting to come. There were so many people around. I just looked around and I found it so daunting."

Ms Loyau-Kennett said her thoughts were to just carry on talking to the man, while several women arriving at the scene tried to shield the victim.

She said: "I wanted him to concentrate on me and make sure he doesn't have a funny idea.

"He (the killer) told me he was a British soldier - he didn't look like a British soldier to me, he wasn't in uniform. But I thought if another one passes by, or is in the area..."

Asked if she was scared, the woman replied: "No - better me than a child.

"Unfortunately, there were more and more mothers with children stopping around, so it was even more important I was talking to him and ask him what he wanted."

Woolwich and Greenwich MP Nick Raynsford praised the extraordinary bravery of members of the public who approached the killers.

The men are in separate London hospitals being treated for injuries after they were shot by police at the scene.

Relatives of the dead soldier have been informed, though he has yet to be named.

One of the attackers behind the barbaric killing was filmed wielding a bloodied meat cleaver, saying: "We swear by almighty Allah we will never stop fighting you.

"In the chilling footage, he explains his terrifying actions.

"We must fight them as they fight us. An eye for an eye, a tooth for a tooth, he is heard to say in the clip," obtained by ITV News.

"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 dont care about you."

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 the damaged car.

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 Kings Troop Royal Horse Artillery and independent companies of the Grenadier and Coldstream Guards.

A car believed to have been used in the attack was taken away during the night.

The blue vehicle, which appeared to have collided with a road sign in John Wilson Street, was covered with a red tarpaulin and taken away by a tow truck.

Former chairman of the Joint Intelligence Committee Baroness Neville-Jones said the security services would be exploring whether the attack was carried out by a lone wolf or by someone with connections to terror groups at home or abroad.

"Clearly, as in this case the perpetrators are still alive, they are going to be questioned. There is going to be a great deal of information available," she said on BBC Radio 4's Today programme.

"There is a much bigger problem, potentially.

"Isolated attacks of the kind we have just seen, of this kind of attack, Im inclined to think is possibly more in the nature of a lone wolf, is particularly hard to deal with because there are very few outward signs beforehand of the nature the intelligence services can pick up."