A series of stabbings at Manchester's Arndale shopping centre are being investigated by counter-terror police, it has emerged.
An updated statement issued by Greater Manchester Police said four people had been taken to hospital with stab wounds following the attacks.
"Specialist officers are continuing to respond to an incident at the Arndale shopping centre in Manchester city centre," the statement 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."
The force added that a man in his 40s who was arrested at the scene on suspicion of serious assault was in custody for questioning.
A multi-agency response has been launched following the incident, with emergency service chiefs holding a gold-level strategy meeting with local government officials.
Officers initially declared a response under operation PLATO, a plan devised to deal with a suspected marauding terror attack - according to the Manchester Evening News - however this was later downgraded.
While the nature of the incident remains unclear, the decision to involve counter-terror police comes two years after the Manchester Arena bombing, in which 22 men women and children were killed at an Ariana Grande Concert at Manchester Arena.
And in May a man was charged with three counts of attempted murder and one count of possessing a terrorist document after a stabbing at Manchester Victoria railway station on New Years Eve.
The current threat level for a terror attack in the UK stands at severe - the second highest rating that ranks an incident as "highly likely".
Following the announcement the city's deputy mayor for policing crime and fire Bev Hughes 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".
The Arndale centre itself was the site of a terror attack in 1996, when the IRA detonated a 1,500kg lorry bomb on the neighbouring Corporation Street, injuring 212 people but killing none.
