Shop was placed on lockdown and customers were ushered to safe area

Dramatic footage has emerged showing a man being restrained on the ground after an elderly customer was stabbed to death in a Poundland branch.

Staff placed the store in Abingdon, Oxfordshire, on lockdown after a man was spotted wandering the aisles with up to four 'foot-long knives' around 11.20am.

One witness claimed he was forced to jump on top of the attacker in a desperate bid to restrain him after he stabbed the shopper, who is thought to have been in his 80s.

It comes just three days after father-of-one David Pethers had his throat slashed at Leytonstone tube station, east London, by a man who allegedly shouted 'this is for Syria'. Police said today's attack was not terrorist related.

A man armed with 'foot long knives' has stabbed a shopper to death at a Poundland store. Above, a knife is spotted on the ground near the scene (right) as police restrain a man (left). Another blade was left in the middle of the road (circled)

Officers rushed to the discount store around 11.22am and were faced with the knifeman who was still at the scene. He was floored by a Taser gun fired by an officer moments later, witnesses said.

The shopper died from his injuries. He is yet to be identified and his next of kin have not been informed, police said.

A short clip uploaded to Twitter appeared to show a plain-clothed police officer and a bystander holding a man down on the pavement following the incident. Two blades, which were allegedly blood-stained, can be seen in the road.

A 36-year-old man from the Abingdon area has been arrested and is currently in custody.

One witness described the moment he pounced on the man in a bid to stop the attack.

Ross Overton, 31, said he sat on the attacker, who he claimed was shouting and screaming.

The produce delivery driver, from Evesham, Worcestershire, said: 'The man walked past my van shouting and screaming but I thought at first that he was on the phone or having an argument with somebody.

'About 30 seconds later I heard a lot of commotion, so I got out my van to check it out.

'I walked around the corner from where I was parked, by the library, and saw he was shouting at an elderly man. Then I saw the knives in his hands. There must have been between two and four.

'He got no attention from the old man so he walked further down the road, shouting, and took a swing at another man.'

Mr Overton followed the attacker into the store, where he was said to carry on shouting abuse at people.

A man armed with 'foot-long knives' was Tasered by police after stabbing a shopper to death at a Poundland shop in Abingdon, witnesses said

Police were called at 11.22am to reports that a man had been stabbed in the shop in Abingdon, Oxfordshire

Staff placed the store in Abingdon, Oxfordshire, on lockdown after the attacker was spotted with up to four blades. Above, police arrive at the scene

The shop was placed on lockdown and customers were ushered to a safe area by staff while the man was wandering in the aisles

He said: 'He went into a shop and started shouting at people, saying "shake my hand and show me some respect".

'The people inside closed the door and told him to drop the knives. They said they would shake his hand if he dropped them.

'After this a police car pulled up and officers threatened to Taser him if he didn't drop his weapons.

'The undercover officer took him down and then I jumped on his back to help keep him restrained. He looked like just a normal person to me.'

A second man was injured nearby and sustained a minor wound to his thumb. Officers are investigating whether this is connected.

Mr Overton added that the man claimed he had also stabbed his flatmate. A spokesman for Thames Valley Police said there was no evidence to suggest the man had hurt anyone prior to the Poundland attack.

The undercover officer took him down and then I jumped on his back to help keep him restrained Ross Overton

Another witness, Ian Collett, said he came out of his shop after hearing a disturbance.

Mr Collett, manager of The Bookstore in the shopping precinct, said: 'I saw this guy walking past the front of the shop holding a blade which was about a foot long. I said to myself "is that real?" It looked like a plastic toy.'

The store has remained closed since the incident and police are guarding the scene.

Thames Valley Police said the attack is not being treated as a terrorist incident at this stage.

A statement said: 'We understand members of the public are concerned, and officers are in the area dealing with the incident and speaking to people to provide reassurance.'

A 65-year-old woman told the Oxford Times she saw the attacker being chased down the street before he was stopped by a police officer who Tasered him.

She said: 'I thought I must be seeing things. I saw this chap with blades sticking out of both hands, maybe kitchen knives.

'There were two men, I think civilians, chasing him and one was on the phone maybe ringing the police. They restrained him outside of the Spar.

'A woman police officer Tasered him and he dropped the knives. Other police came soon after.'

Forensic officers remained at the scene on Monday evening and the area was cordoned off to the public

It was later confirmed by witnesses at the scene of the Poundland murder that the victim was a customer who was shopping when the knifeman came across him

Forensic officers could be seen inside the store carrying out test after the incident earlier today

Liz Cummings posted on Twitter: 'Very distressing morning in work. Stabbing outside my shop in Abingdon. RIP to the gentleman who was in the wrong place at the wrong time.'

Another Twitter user, Joanna, posted: 'Watching everything that happened today in Abingdon from my office window was terrifying. Rest in Peace.'

Taxi driver Colin Dobson was collecting a passenger when he was surrounded by three police cars and officers ran into the store.

He said: 'Someone had run out of Poundland and down the other end of the precinct and had been apprehended on the High Street.'

Jim Sayers took to Twitter and said: 'Pray for @ThamesVP Stabbing in Abingdon Poundland this morning.'

Rory Freeman, the police area commander said: 'Members of the public are shocked and upset by an incident that happened today in a very public place.

'We would like to reassure people that this is not being treated as a terrorist incident. I know people are scared in light of recent events but this is not the case.

'Police are working to establish the exact circumstances surrounding what happened. I would personally like to thank the public for their support as this investigation takes place.'

Jim McCarthy, Poundland CEO, added: 'We are naturally shocked that one of our customers was attacked and has subsequently, despite the best efforts of colleagues, customers and paramedics, sadly passed away.

'Our sympathy and thoughts centre on the family of the deceased and, of course, with other customers and colleagues who were in the store at the time of this terrible incident.'