Terror probe after mass stabbing at Manchester shopping centre

England on Oct 11, 2019, following a series of stabbings. (Photo: LINDSEY PARNABY / AFP)

The man in his 40s was "lunging and attacking people" with a large knife in the Arndale shopping centre, Police Chief Russ Jackson said.

"Although the injuries are nasty, we are told that, thankfully, none are life-threatening."

The suspect was detained within five minutes and initially arrested for assault, before this was changed to an accusation of preparing and instigating an act of terrorism.

"We do not know the motivation for this terrible attack. It appears random, is certainly brutal and of course extremely frightening for anyone who witnessed it," Jackson said.

Greater Manchester Police previously said in a statement: "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."

The attack happened at the Arndale shopping centre in the heart of Manchester, near where an Islamist extremist suicide bomber killed 22 after an Ariana Grande concert in 2017.

"This is bound to bring back memories of the awful events of 2017," said Jackson.

"We do not believe there is anyone else" involved in the attack, he added. "We do not believe there is a wider threat at this time."

"VISIBLY SHAKEN"

Local reports said the mall was evacuated, with large numbers of police and paramedics in attendance.

A video circulating on social media showed a police officer pinning a person down on the ground outside the shopping centre. Another police officer is seen pointing what looks like a taser at the person.

A shop worker who gave his name only as Jordan, 23, told Britain's domestic Press Association news agency that "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".

Two women - one of them aged 19 - were taken to hospital with stab wounds. They were said to be in a stable condition following the attack, which happened shortly after 11am local time.

A man in his 50s was also being treated while the fourth victim, a woman in her 40s, did not require treatment, police said.

British Prime Minister Boris Johnson said he was "shocked" by the incident.

"Shocked by the incident in Manchester and my thoughts are with the injured and all those affected," he said in a tweet. "Thank you to our excellent emergency services who responded and who are now investigating what happened."

Among the pictures circulating on social media was one of paramedics screening off a cafe to treat victims after the shopping centre was evacuated.

Freddie Houlder, 22, said he was in the centre when he heard "a load of screams" before a woman told him she was nearly stabbed.

"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.

"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 had already been the scene of a terror attack in 1996 when the largest peacetime bomb ever detonated in Britain injured 212.

The 1,500kg truck bomb, planted by the Provisional Irish Republican Army, caused an estimated £770 million (US$970 million) damage, and led to the centre being completely redeveloped.