Video: UK police treating Manchester stabbing attack as terrorist investigation

British police confirmed on Tuesday they were treating a stabbing attack which injured three people at Manchester's Victoria train station as a terrorist investigation, as an eyewitness recalled the attacker shouting "Allah" during the attack.

Earlier on Tuesday police had said the investigation was led by counter-terrorist experts but they were "keeping an open mind".

"We are treating this as a terrorist investigation," Chief Constable Ian Hopkins told reporters.

BBC Producer Sam Clack, who was on the scene, said he felt nervous after hearing the attacker shout "Allah" (the Arabic name for the Abrahamic God) in a sentence he could not recall.

The stabbings occurred at about 8:50 pm.

Britain is currently on its second-highest threat level of severe, meaning an attack is considered highly likely and security officials say they are facing record levels of work in countering Islamist militants as well as far-right extremists after four major attacks last year.

Manchester itself was the scene of a suicide bomb attack in May 2017 that killed 22 people as they left an Ariana Grande concert.