A woman was killed and five other people injured when a man with suspected mental health issues went on a rampage with a knife in central London, an attack police said could be linked to terrorism.
Armed police were called at 10:33 p.m. (2133 GMT) after a man with a knife started to attack people in London’s Russell Square, an elegant park near the site of a 2005 suicide bombing.
“Early indications suggest that mental health was a factor in this horrific attack,” said London Metropolitan Police Assistant Commissioner Mark Rowley.
“We are keeping an open mind regarding the motive,” said Rowley, who is Britain’s most senior anti-terrorism officer. He earlier said one line of inquiry was that terrorism was a motive.
Police, who arrived within five minutes of being called, used a Taser electric shock gun while detaining the 19-year-old suspect. He was later formally arrested on suspicion of murder.
The investigation was being handled by homicide command with support from counter-terrorism officers, Rowley said.
The victim was treated at the scene but pronounced dead a short time later. The other injured – one woman and four men – were treated in hospital. Three were later discharged.
Police cordoned off the southern part of the square, which sits at the heart of London’s university area and is close to landmarks such as the British Museum, for several hours as forensics officers examined the attack scene.
Later, workmen hosed blood off the pavement.
Britain says its terrorist attack threat level remains at “severe”, the second-highest level, meaning a strike is “highly likely”. Police had already promised to deploy more armed officers in the capital after a spate of deadly attacks in France, Germany and Belgium.
Attacks across Europe have heightened tensions between some communities, raised questions about the European Union’s border policies and bolstered support for anti-EU far-right groups.
Police chiefs and security bosses have repeatedly warned that Islamic State fighters want to carry out attacks against Britain, a close ally of the United States.
London’s first Muslim mayor, Sadiq Khan called for vigilance and there was an increased police presence in the capital.
“The safety of all Londoners is my number one priority and my heart goes out to the victims of the incident in Russell Square and their loved ones,” he 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.”
Just hours before the Russell Square attack, London’s police chief said that he would deploy an additional 600 armed officers across the capital to protect against any attacks.
London counter-terrorism police chiefs have previously warned that Islamic State was seeking to radicalise vulnerable people with mental health issues to carry out attacks. In some operations, police commanders have taken advice from specialist psychologists.
Islamist militants hit London with coordinated suicide bombings on July 7, 2005, killing 52 people. One of the bombs detonated on a bus close to Russell Square.
Since then, dozens of plots have been foiled and there have been smaller-scale attacks, such as the beheading of an off-duty soldier by militant Islamists in a London street in May 2013.
A man who attacked passengers at a London underground train station in December was jailed for life earlier this month. The judge said the attacker was suffering from paranoid schizophrenia at the time of the offence but may have been motivated by events in Syria.