London knife attack leaves 1 dead, 5 hurt

An elderly American woman was on Thursday stabbed to death and five others including foreigners were injured when a suspected mentally ill teen went on a rampage with a knife in central London, in an attack police said could be linked to terror.

A 19-year-old Norwegian national of Somali origin was arrested using a Taser gun on suspicion of carrying out the "random" mass knife attack at Russell Square near the popular British Museum in central London at 10.39 pm (local time yesterday), Scotland Yard said.

An American woman, in her 60s, was killed in the attack that also injured two other women and as many men, police said but there was "no evidence of radicalisation" in the assault. The victims include Australian, American, Israeli and British citizens.

London Mayor Sadiq Khan called for "calm and vigilance" the people, whose safety he said "is my number one priority" as Londoners woke up this morning to notice an increased presence on the streets of officers following the attack that comes days after a public warning against Islamic State-inspired assaults.

The attack also came on a day Scotland Yard announced that 600 additional armed officers will be deployed around London's major sites, including British Museum, as part of anti-terror plans in the wake of ISIS attacks in Europe, and days after Metropolitan Police chief Sir Bernard Hogan-Howe said a terror attack in the United Kingdom was a case of "when, not if."

However, Metropolitan police Assistant Commissioner Mark Rowley in a statement outside Scotland Yard headquarters in London said that "at this point we believe this is a spontaneous attack and the victims were selected at random".

The police were called following reports of a man armed with a knife was attacking people and "armed officers attended the scene within approximately five minutes of receiving the first call".

An eye witness who saw the events unfold from her hotel window told BBC she saw a black man running down the street. Other witnesses said that when the "large man" stabbed the people he did not shout or scream anything.

"A Taser was discharged during the arrest of the suspect, a 19-year-old man. No shots were fired. After receiving treatment at hospital he currently remains in custody at south London police station," a Scotland Yard statement said.

Two victims remain in hospital but are not suffering from life-threatening injuries while the others have been discharged, police said, adding early indications suggested that "mental health was a factor in this horrific attack."

While Metropolitan police earlier said "terrorism is one possibility being explored at this stage" in the wake of a string of recent attacks in Europe, the latest from the force is that "we continue to focus our lines of inquiry on mental health while retaining an open mind regarding the motive".

Khan said his "heart goes out to the victims of the incident and their loved ones" and appealed to the public to report anything suspicious to the police.

Rowley, in charge of the force's specialist operations, said: "So far we have found no evidence of radicalization or anything that would suggest the man in our custody was motivated by terrorism."

The Metropolitan Police Service's Homicide and Major Crime Command is leading the investigation, supported by officers from the Counter Terrorism Command.

The eyewitness, who saw a black man running down the street, saw: "I could hear the policeman screaming 'stop, don't move, don't go any further, just stay where you are', and he turned round and continued running."

Hogan-Howe praised the force's "swift response" that "undoubtedly helped to prevent more people from getting injured".

He added: "Our investigation is moving very quickly and our detectives have been working hard throughout the night. As we have already made clear, mental health remains a substantial focus for our investigation.

"We will protect our capital and those who live, work and visit our city."

Ambulances and police vans were seen stationed outside Imperial Hotel, near the Russell Square Underground station. The suspect himself was taken to hospital after being immobilised with a Taser electroshock gun.

Khan said: "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.

Thursday's mass stab attack came two days after a mentally unwell 30-year-old paranoid schizophrenic man was jailed for life for trying to behead a commuter in an Islamic State inspired knife attack at a London tube station last December.

Since August 2014, the terror threat level in Britain has been "severe" -- the second highest level, meaning an attack is "highly likely".

In the July 7, 2005 terror attacks in London, one of the suicide bombs which hit the city's public transport system was detonated on the London Underground between Russell Square and King's Cross. While 7/7, which killed 52 people, was the last large- scale terrorist attack in Britain, there have been a string of smaller incidents since.