The incident took place at the Arndale Centre at around 11:15 a.m. local time (6:15 a.m. ET), where a man who was carrying a "large knife" began "lunging and attacking people", Assistant Chief Constable Russ Jackson of Greater Manchester Police said.
A spokesperson for Greater Manchester Police said: "We were called to reports of a multiple stabbing at the Arndale shopping centre at 11.15am".
"We do not know the motivation for this bad attack", Greater Manchester Police Assistant Chief Constable Russ Jackson said.
Footage posted online appeared to show one police officer restraining a suspect on the floor as another stands over him pointing a taser.
"Soon after, security staff told all retail staff to close their doors and move the public to the back of the stores", he added.More news: Jane Fonda arrested protesting climate change in Washington
"Shocking scenes right out of a movie but real people with injuries".
Mr Jackson went on to say: "The man, in his forties, was initially arrested on suspicion of serious assaults".
The force previously said two women, including a 19-year-old, were in a stable condition in hospital, while a man in his 50s was being treated in hospital for stab wounds.
Tina Concar, 52, from Miles Platting, Manchester, said she was evacuated from the Arndale Centre after the attack.
David Allinson, Centre Director for Manchester Arndale, told the Manchester Evening News that there had been a serious incident.More news: Chris Cuomo Says His Pronouns Are ‘She, Her, and Hers’
Counter Terrorism Police North West are now investigating the motivation behind the attack.
"Officers are in attendance and early enquiries suggest that several people have been stabbed", Greater Manchester Police said.
"She said this guy was trying to stab random people", Houlder said.
The man was "lunging and attacking people" with a large knife, according to the police statement.
Manchester was the location for Britain's most deadly attack in recent years when Salman Abedi, a 22-year-old Briton born to Libyan parents, killed 22 people in May 2017 when he blew himself up at the end of a pop concert by Ariana Grande at the Manchester Arena, not far from the Arndale center.More news: Sharks bring back 40-year-old Patrick Marleau for 2nd stint
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.
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