At least four people have been injured in a stabbing at the Arndale Centre in Manchester, police have said.
A man, 41, is being held on suspicion of terror offences after three people were stabbed and a fourth was hurt.
The centre was evacuated after the attack at about 11:15 BST, during which police said a man with a large knife “started lunging and attacking people”.
Two police community support officers (PCSOs) tried to confront the attacker before being chased.
Speaking at a press conference, Assistant Chief Constable Russ Jackson suggested that up to five people were injured.
“The man attacked people around him,” he said.
“Although the injuries are nasty, we are told that, thankfully, none are life-threatening.”
In a tweet, Prime Minister Boris Johnson said: “Shocked by the incident in Manchester and my thoughts are with the injured and all those affected.”
ACC Jackson said: “At 11:15 BST this morning, a man entered the Arndale shopping centre in Manchester city centre.
“He was armed with a large knife and, as he entered Exchange Court, began lunging, attacking people with the knife.
“Two unarmed police community support officers were in Exchange Court and attempted to confront the attacker.
“He then chased them with the knife as they were calling for urgent assistance.”
Two women, including a 19-year-old, are in a stable condition in hospital, while a man in his 50s is also being treated in hospital for stab wounds, police said previously.
One patient suffered “serious” injuries, North West Ambulance Service added.
A shop worker, who gave his name only as Jordan, 23, said: “A man was running around with a knife lunging at multiple people, one of which came into my store visibly shaken with a small graze.
“Soon after, security staff told all retail staff to close their doors and move the public to the back of the stores.”
Jordan, who has only been working at the centre for a few months, said the attack took place on the ground floor.
Freddie Holder, 22, from Market Drayton, Shropshire, said he heard “a load of screams just outside” the shop he was in.
He said a woman then came into the shop and told others “a guy just ran past the shop and tried to stab me”.
“Luckily she had quite a thick jacket – she thought originally it was a fake knife because of how easily it grazed off but police came in and said it was a real knife and she burst into tears,” he added.
“I’m still kind of in shock from it, I’m shaking a little bit… all shops had been locked down just for safety.
“The police arrived extremely quickly, which was very lucky.”
Social media posts show a large number of officers at the scene and a suspect being Tasered.
An image sent to the Manchester Evening News appears to show a patient being treated at a Starbucks cafe in the centre.
Police originally said five people had been stabbed but have since clarified the number of people hurt.
A GMP spokesperson said: “In these early stages, we are keeping an open mind about the motivation of this terrible incident and the circumstances as we know them.
“Given the location of the incident and its nature officers from Counter Terrorism Police North West are leading the investigation as we determine the circumstances.”
At the scene
By Kaleigh Watterson, BBC News Online
There’s a helicopter hovering up above and various police cars stationed around, with a large cordon set up close to Selfridges.
This should be a busy Friday afternoon of shopping in Manchester, and there’s an eerie atmosphere as the city centre’s largest mall was deserted.
People have gathered around watching the police activity, while others seem to be carrying on with their day.
There has been confusion from some as not everyone’s been told why the Arndale is closed, particularly on busy Market Street where the centre’s doors were closed with no signs put up.
Deputy Mayor of Greater Manchester Bev Hughes praised the emergency services.
Labour councillor Pat Karney, for Harpurhey and Collyhurst, tweeted: “Armed police on guard. Shocking scenes right out of a movie but real people with injuries.”
David Allinson, centre director of Manchester Arndale, said: “The centre has been evacuated while police investigate the incident.
“We are unable to comment any further as the incident is currently being handled by Greater Manchester Police, who we will continue to support with their investigation.”
Councillor Nigel Murphy, deputy leader of Manchester City Council, said the “incident is under control” and advised people to stay away from the scene to enable the emergence services to carry out their work.
“We would encourage people not to speculate about this incident but to refer to trusted official sources for updates,” he added.
GMP tweeted: “A rendezvous point has been established at Piccadilly Gardens, so you will see a large police presence in this area. Please don’t be alarmed.”
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