Four people have been injured in a knife attack at the Arndale Centre in Manchester city centre.
A man was seen “running around with a knife lunging at multiple people”, according to one witness.
Police said three people had been stabbed and a fourth was also hurt. A man in his 40s has been arrested.
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.”
Counter-terror officers are “keeping an open mind” about the motive for the attack, Greater Manchester Police (GMP) said.
The shopping centre has been evacuated and trams have stopped operating at Exchange Square outside the entrance.
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.
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.
One patient suffered “serious” injuries, North West Ambulance Service said.
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.
The arrested man is being held on suspicion of serious assault.
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.”
