Five people have been stabbed in an attack at the Arndale Centre in Manchester city centre.
The shopping centre has been evacuated and trams have stopped operating at Exchange Square outside the entrance.
Police said there had been no reports of fatalities and counter-terror officers were leading the investigation but “keeping an open mind”.
A man in his 40s has been arrested on suspicion of serious assault.
A spokesperson for Greater Manchester Police said: “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.”
Social media posts have shown a large number of officers at the scene and the suspect being Tasered.
An image sent to the Manchester Evening News appears to show a patient being treated by a Starbucks cafe in the centre.
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.”
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.”
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 Houlder, 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.
Please include a contact number if you are willing to speak to a BBC journalist. You can also contact us in the following ways:
- WhatsApp: +44 7756 165803
- Tweet: @BBC_HaveYourSay
- Send pictures/video to
- Upload your pictures / video here
- Text an SMS or MMS to 61124 or +44 7624 800 100