Counter terror police are investigating after a knifeman ran amok in Manchester's Arndale shopping centre 'lunging at people' at random.
Four people were taken to hospital with injuries following the attack at around 11am on Friday.
Police had previously reported that five people had been injured.
A 19-year-old woman– was taken to hospital with stab wounds. Another woman was also taken to hospital with stab injuries. Both their conditions are described as stable.
A man in his 50s has also been taken to hospital with stab wounds.
A fourth victim – a woman in her 40s - who was not stabbed – has been assessed and did not need to go to hospital following assessment by paramedics.
A man in his 40s – who was arrested at the scene on suspicion of serious assault – remains in custody for questioning.
Witnesses described a scene of terror as shoppers, some with injuries, sought refuge in stores.
A spokesman for Greater Manchester Police said: "Specialist officers are continuing to respond to an incident at the Arndale shopping centre in #Manchester city centre.
"We can confirm that five people have been stabbed and taken to hospital.
"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.
"A man in his 40s – who was arrested at the scene on suspicion of serious assault – remains in custody for questioning."
North West Ambulance Service (NWAS) said one patient of the five had suffered "serious" injuries.
NWAS tweeted: "We have treated four patients, including one patient with serious injuries and all have been taken to hospital."
Two ambulances and four incident response units from North West Ambulance remain parked outside the Next store, opposite The Printworks.
Bev Hughes, Greater Manchester's deputy mayor for policing, crime and fire, said: "I want to praise Greater Manchester's emergency services for their swift and professional action. Our thoughts are with the five people injured. The scene has been secured and all emergency services are engaged in ensuring public safety - the investigation is ongoing.
"Anyone with information should call police on 101 quoting incident number 1055 of 11/10/2019, or the independent charity Crimestoppers, anonymously, on 0800 555 111."
A shop worker, who gave his name only as Jordan, 23, told the PA news agency: "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 Houlder, 22, from Market Drayton, was in the Arndale Centre when 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".
Mr Houlder added: "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 said he was evacuated several minutes later at which point he saw "a bunch of curtains covering someone seriously injured or dead, I don't know".
"I definitely don't think it was gang violence because this guy was going around trying to stab random people, I believe."
The Arndale Centre is just a few hundred yards from the Manchester Arena and Victoria railway station - both of which have been the scene of recent terror attacks.
Twenty-two people were killed in May 2017 when Salman Abedi detonated a suicide bomb in the Manchester Arena following an Ariane Grande concert - the youngest victim was just eight years old.
Last New Year's Eve, three people including a police officer were seriously injured after a 25-year-old man launched a knife attack on passers-by.
The suspect was heard to shout "Allah" and "Long live the Caliphate" during the incident - he was arrested on suspicion of attempted murder and his since been detained under the Mental Health Act.
In 1996, the Arndale Centre was damaged in a major bomb attack by the IRA in which a 1,500-kilograms device loaded on a lorry was detonated on Corporation Street.
More than 200 people were injured in the explosion, although there were no fatalities.