AN American woman in her 60s was knifed to death and five others injured during a bloodbath attack carried out by a Norwegian-Somali man in central London last night.

Witnesses described victims "screaming and covered in blood" following the rampage in which the woman was brutally knifed by a man around 10.30pm.

Police sources confirmed the attacker hailed from Norway and is of Somali descent - and added that he has shown no signs of radicalisation.

Other terrified onlookers described the crazed knifeman chasing pedestrians and "lunging for anyone he could see" as police confirmed mental health was a likely factor.

A 19-year-old man was arrested at the scene after being tasered by police in Russell Square as officers yelled: "Put it down."

It comes as dramatic footage emerges of the suspect being arrested by police last night.

Witnesses reported the dying woman's final words were: "He's still here, he's still here."

32 Hotel guest Chanel Britton, 19, of Barnsley, caught the action on her mobile phone in central London last night Credit: The Sun

32 She told The Sun: “We had just got back and were sat having a drink at the window. Then we saw this man run down the street followed by police with their guns out” Credit: The Sun

32 The man was hit by a taser outside the Clarendon Hotel after running away down Bedford Place. Credit: The Sun

32 A woman, said to be American, was stabbed to death by a man in Russell Square last night. Dramatic Images showed emergency services battling to save her life Credit: The Sun

32 Emergency services rushed to the scene where the American woman was stabbed to death and five others injured Credit: The Sun

32 The other victims hailed from Australia, Israel, Britain and the USA, police confirmed this afternoon Credit: The Sun

32 Forensic teams removed the body of the victim this morning as the full horror of the knife rampage emerged Credit: PA:Press Association

32 A forensic officer examines what is believed to be the knife used in the attack last night

32 Blood was visible on the forensic team's tent as they scoured Russell Square for evidence in the early hours of the morning Credit: Getty Images

32 The scale of the knife attack was made tragically clear with the sight of blood covering the forensic team's tent Credit: London News Pictures

32 Detectives removed items from the scene for forensic analysis as witnesses began to speak out about the horror they witnessed on the capital's streets Credit: London News Pictures

32 A bloodied marks remains on the pavement near to where the Norwegian man was tasered and arrested by police last night Credit: News Group Newspapers Ltd

Those injured were British, Australian, Israeli and another American.

London mayor Sadiq Khan urged people to remain "calm and vigilant".

The horrific incident happened just yards from where one of the 7/7 terror attack bombs detonated in 2005.

One witness described a "chubby" white man in a t-shirt and shorts acting suspiciously.

Fernando, 40, a paralegal from Brazil, said: "I was cycling by and people screamed at me to stop. It was a Spanish family who approached me.

"It was a mother and father and two sisters. Then I saw a white lady, in her sixties, slumped against the railings.

"She had her head in a Spanish woman's lap, the lady, who was trying to keep her alive by talking to her. They were not related, I think the Spanish family were just passing by.

"She had been stabbed in the back. She was bleeding. There was an English man who was white, I'd say around 45. He had been stabbed in the side.

"Then there was another lady. I didn't know her nationality but I think she was white. She was in her twenties. She had been stabbed in her arm.

32 A policeman lays a bunch of flowers at the scene this morning. Five more were injured, including three men and two women Credit: PA:Press Association

32 Flowers were laid at the scene of the knifing throughout the day on Wednesday as police continued to guard the area Credit: Getty Images

32 New accounts of the devastating attack revealed the dying women warned Spanish tourists who were comforting her that her killer was still on the loose Credit: News Group Newspapers Ltd

32 A knife attack in Russell Square, central London, has left one dead and at least five injured, including three men and two women Credit: London News Pictures

32 Armed cops and paramedics were called to the scene after witnesses reported seeing a man attacking people with a knife and "lunging at anyone he could see"

32 The attack took place in the Bloomsbury area of central London, just yards from Russell Square's Imperial Hotel

32 A Brazilian witness, named only as Fernando (pictured), said the attacker had been a "chubby white man wearing a t-shirt and shorts" Credit: Dean Wilkins

"The old lady had been stabbed in the back.

"The lady from the Spanish family told me that the guy had passed by, running, stabbing people. They said he had been wearing black shorts and a white t-shirt and was chubby.

"They said they thought he was white but he was covering his face like this [with arm] I think as he was stabbing people like this."

Police confirmed terrorism was "one line of inquiry that we should explore".

A knife used in the attack was pictured lying on the ground next to the murder scene - apparently tossed to the floor by the killer.

Three men and two woman were also injured - two of whom remain in hospital following the horrific mass stabbing near the capital's Imperial Hotel.

One witness said: "I heard a scream, and then we went to the park and I saw a girl lying on the floor with blood coming from her back. Another girl had blood on her arm.

"They all spoke Spanish so I guess they were a group. I only saw the victim and the girl with the arm stabbed from that group.

"I just saw blood just next to her. She was lying on the floor with a friend hugging her."

What we know so far about the Russell Square stabbings:

A 19-year-old Norwegian man of Somali descent attacked six people with a knife in central London's Russell Square at around 10.30pm last night

Detectives could see no evidence that he had been radicalised

An American woman in her 60s was killed and another five injured. Two remain in hospital.

The five injured hail from Britain, Australia, Israel and the USA.

The attacker has been arrested on suspicion of murder and is being held at a South London police station.

Police confirmed they were not ruling out the incident being terror-related and said they believed mental health was a key factor.

Images emerged this morning of police forensic teams removing the body of the victim, while blood was clearly visible on the forensics tent.

The suspect is in custody at a South London police station after being arrested on suspicion of murder.

Midlanders Fay and Ken Clegg were walking back from Shaftesbury Theatre at the time of the attack.

They told The Sun: "We saw what we thought were blue flashing lights. The bar was absolutely packed but we didn't know what was happening just outside.

"It's shocking to think it happened so close. We must have just missed it."

Emma Pigdon, 40, had been to the theatre with her husband Mark, also 40. The couple, visiting from Durham, had been celebrating their birthday.

Teaching assistant Emma said: "We were on our way back from the theatre when we saw a woman being worked on by the emergency services.

"I couldn't tell if she was wearing a patterned dress or if it was blood. She looked so tiny I thought she was a teenager.

"We went to get a coffee and when we came back she was covered by a sheet.

"There was also a guy leaning against railings with his top off. He had a bandage around his lower chest."

32 Heavily-armed Met Police officers were sent onto the streets this morning to reassure the public following last night's knife attacks in Russell Square Credit: AP:Associated Press

32 The Met launched a new anti-terror armed police unit yesterday - just hours before the knifeman began his deadly rampage Credit: Getty Images

Rehana Azam, 42, of Darlington, was staying at the Imperial Hotel when the incident happened.

She said: "I looked out my window and thought somebody had collapsed and saw a paramedic performing CPR on the person on the ground.

"More and more emergency vehicles, including police cars and ambulances, arrived and I saw a number of people being treated.

"But then it became clear the person being treated for CPR had died as they put a blanket over them.

"I saw another person - who I think was a male - being taken into an ambulance on a stretcher. It was awful.

"A police officer and a paramedic were comforting someone who was very distressed, it could have been a family member of the victim. They were very upset."

He was just lunging at people randomly and stabbing them. He was just going for anyone he could see.

Another witness told the Evening Standard: "The police came to the hotel and a guest was telling them what he saw.

"He said there was a madman running around with a knife just lunging at people randomly and stabbing them. He was just going for anyone he could see.

“I ran out to look and saw all the paramedics around one woman who was badly injured, trying to help her."

A guest at the hotel described seeing a man "parading" up and down the pavement in a biker helmet, while another said they witnessed a second man speeding off on a motorcycle.

Met Police Chief Sir Bernard Horgan-Howe hailed his officers for preventing more bloodshed last night.

He said: "I am proud that last night our specialist firearms officers were on the scene in six minutes and, using only a Taser, detained the subject.

"That demonstrates our commitment to use force in a professional and proportionate way.

"Their swift response undoubtedly helped to prevent more people from getting injured."

Last night, anti-terror chief Mark Rowley, a Met Police Assistant Commissioner, said "mental health was a significant factor" in the attack but that "terrorism was still a line of inquiry".

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Speaking outside Scotland Yard, Commander Rowley said: “Police were called just after 10.30pm last night to reports of a man, armed with a knife, assaulting people in Russell Square, Camden.

“Armed officers arrived at the scene within five minutes, they discharged the Taser whilst confronting and arresting the suspect.

“Six people have been injured, including the one woman who sadly died at the scene, and the others have received various injuries.”

He also confirmed the Met's new fast response anti-terror unit would be on the capital's streets today to reassure members of the public.

He added: “Early indications suggest that mental health is a significant factor in this case and that is one major line of inquiry.

“But of course at this stage we should keep an open mind regarding motive and, consequently, terrorism as a motivation remains but one line of enquiry for us to explore.”

32 The attacks took place near to London's Imperial Hotel in the capital's Bloomsbury area Credit: Alamy

32 Cops arrested and tasered a man following the stabbings outside London's Imperial Hotel at around 10.30pm last night

32 The female victim, in her 60s, was treated at the scene but was pronounced dead not long after Credit: UKNIP

32 Another witness has claimed that the women involved were with two men and that they were all speaking Spanish Credit: EPA

London mayor Khan said: "I urge all Londoners to remain calm and vigilant. Please report anything suspicious to the police‎. We all have a vital role to play as eyes and ears for our police and security services and in helping to ensure London is protected.

"Our police officers are doing an incredibly difficult job on our behalf and they have my full support."

The female victim, in her 60s, was treated at the scene but was pronounced dead not long after.

Police have said that it is “inappropriate at this time to give any more personal details about her”.

Lauren Britty, whose brother allegedly witnessed the attack, claimed on Twitter that the woman may have been part of a hen party.

Did you witness last night's attack? Do you know the attacker? Get in touch with The Sun's news desk on 0207 782 4102 or email us on Daniel.Collins@the-sun.co.uk

Another witness has claimed that the women involved were with two men and that they were all speaking Spanish.

A receptionist at the nearby Imperial Hotel in Russell Square said: “We don’t know what’s going on.

“The police have been in the square since about 10.30pm.”

Additional police units have been deployed to the area.

32 Forensic teams scoured the area last night as the full scale of the attack was beginning to emerge Credit: London News Pictures

32 The attack came barely hours after the Metropolitan Police announced it was to launch a new fast-response anti-terror unit Credit: BBC

I think there's been an incident outside the Imperial Hotel on Russell Square in London. :( #London pic.twitter.com/t0plUsWM1p — Stuart Kenny (@StuartKenny33) August 3, 2016

32 Witness described seeing a "dark skinned" man being held down by police after he had been tasered Credit: BBC

Pol O'Geibheannigh, 45, was walking back from the cinema when he saw a massive police presence and a woman lying in a pool of blood.

He said: "I just knew right away that this is not right. You just don't see armed police around this area.

"This was just wall to wall with armed police. You could see a woman on the floor.

"There was dark matter around her, which was obviously blood.

"She was lying in a pool of blood with a red blanket on top of her."

32 Additional police units have been deployed to the area to reassure locals terrified after the bloody attack Credit: BBC

32 Police said terrorism is being explored as a possible motive behind the attacks but also said mental health was believed to be a factor Credit: BBC

32 One witness said he believed the groups was on a hen do when it was attacked in the central London area Credit: London News Pictures

32 The Met Police unveiled its new fast response anti-terror unit yesterday. The officers will be on London's streets today to reassure the public Credit: PA:Press Association

Twenty six people were killed when Germaine Lindsay, 19, detonated a suicide bomb on a Piccadilly line Tube as it moved between King's Cross station and Russell Square in July 2007.

A bomb was detonated on the same day at nearby Tavistock Square, killing six.

Yesterday's attack came on the same day the Met announced it was to put more armed officers on public patrol as part of anti-terrorism plans.

Do you know any of the victims? Get in touch with The Sun's news desk on 0207 782 4102 or email us on Daniel.Collins@the-sun.co.uk

A newly-formed unit comprised of heavily-armed anti-terror police was unveiled to respond quickly to lone-wolf terror attacks.

On Sunday Metropolitan Police chief Sir Bernard Hogan-Howe warned that a terror attack in the UK was a case of "when, not if".

Counter-terror police are also probing the attempted abduction of a serviceman at knifepoint from a road near RAF Marham in Norfolk on July 20.