SUPPORTERS of the barbaric Islamic State are celebrating the horrific knife attack which left a woman in her 60s killed and five others injured during a bloodbath in central London believed to be terror-related.

Sick messages were posted on an ISIS-linked social media channel spreading the news of the attack.

11 Messages from IS-linked social media channels spreading the news of Russell Square's knife attack believed to be terror related Credit: Twitter

One Arabic account, which posted snaps from the scene, wrote: "And here you have a picture of the site where the stabbing took place, Russell Square in the centre of 'Christendom' London."

11 Snaps of the horrific attack were shared to the group Credit: Twitter

11 News of the knife attack in Russell Square quickly spread to IS supporters Credit: Twitter

Another account added: "It's nice to wake up to such news."

Further messages make references to Sharia, which is the law of Islam and filtrate more IS news and propaganda.

Last night, police were called to Russell Square in London after reports of an attack by a knife-wielding man.

11 A body is removed from the scene in Russell Square, central London, after a knife attack in which a woman in her 60s was killed and five people were injured Credit: PA:Press Association

11 They claim the area was surrounded by "wall to wall police" Credit: PA

11 Witnesses have said they saw the woman lying in a pool of blood while others tried to help her Credit: London News Pictures

11 The suspect is understood to have "significant mental health issues" Credit: PA

11 The stabbing, which police have not yet ruled out could have been terrorism related, happened in Russell Square Credit: London News Pictures

Witnesses described victims “screaming and covered in blood” following the rampage in which the woman – believed to be a Spanish speaker enjoying a hen do – was brutally knifed around 10.30pm last night.

Another terrified onlooker described the crazed knifeman “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 – just yards from where one of the 7/7 terror attack bombs detonated in 2005.

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 ground by the killer.

What we know so far about the Russell Square stabbings:

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

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

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.

Three men and two woman were also injured and remain in an unknown condition 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."

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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."

11 The attack brought back memories for many people of the 7/7 bombings when an explosive was set off on a bus in the area Credit: Reuters

11 One woman was killed and five other people injured in a knife attack in London last night Credit: London News Pictures

11 Armed police flooded the area in the wake of the attack and forensics remain at the scene this morning Credit: Getty Images

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 enquiry".

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.”