Updated 12.15pm

A WOMAN KILLED in a knife attack in central London was a US citizen, the Met Police has said.

The nationalities of the two men and three women also injured in the attack have been given as Australian, American, Israeli and British.

Two of the victims remain in hospital while the others have been discharged.

The American woman killed in the attack was aged in her 60s.

A 19-year-old Norwegian man of Somali descent has arrested by police on suspicion of murder.

Speaking a short time ago, commissioner of the Met Police Bernard Hogan-Howe said that mental health remains the “substantial focus” of the investigation.

Source: Yui Mok/PA

Scotland Yard has ruled out earlier speculation that the incident was terror related.

The Met Police’s assistant commissioner Mark Rowley has said that there is “no evidence of radicalisation or that the man was motivated by terror”.

Police received a number of calls after 10.30pm about a man armed with a knife assaulting people at Russell Square in Camden. Armed officers attended within five minutes and a Taser was discharged on a 19-year-old man.

No shots were fired. After receiving treatment in hospital, the man was taken into police custody. In an updated statement this morning.

The attack

Paramedics attended to the woman who was killed in the attack, but she was pronounced dead at the scene.

Source: Yui Mok/PA

‘A tragic incident’

The main investigators in the case are from the Metropolitan Police Service’s Homicide and Major Crime Command but they are being supported by officers from the Counter Terrorism Command.

“This was a tragic incident resulting in the death of one woman and five others being injured,” said assistant commissioner Mark Rowley.

Early indications suggest that mental health was a factor in this horrific attack. However, we are keeping an open mind regarding the motive and terrorism remains one line of inquiry being explored.

“As a precautionary measure, Londoners will wake up this morning to notice an increased presence on the streets of officers, including armed officers today. We would urge the public to remain calm, alert and vigilant.”

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A police officer and sniffer dog outside King's Cross St Pancras underground station in London. Source: Jonathan Brady/PA

Witnesses

Xavery Richert, 22, a French tourist staying in a youth hostel on the square, told AFP:

I was buying a beer when I heard a woman shouting who was being chased by a man. I thought it was a bag snatching… she was not hurt. I came out for a cigarette, I went back, there were firefighters, police, and then I saw the body under a sheet.

Russell Square resident Constantine Somerville added: “It’s such a safe area and very quiet, especially at night — why would somebody commit an attack in such a quiet area?”

London Mayor Sadiq Khan urged “calm and vigilance” this morning.

“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.”

Khan said police were seeking “to establish the full facts including motives” for the attack and said his “heart goes out to the victims” and their loved ones.

- First published 6.50am

With reporting by AFP and Michelle Hennessy.