The incident is believed to have happened at the Kingsbury Halal Butchers just 100 yards from Kingsbury Tube station and in a busy shopping street.
A Scotland Yard spokesman said: ‘Police were called at approximately 8.40am to a disturbance in Kingsbury Road, Kingsbury.
Crime scene: The multiple stabbing is believed to have taken place at Kingsbury Halal Butchers
Cordoned off: Metropolitan Police officers at the scene of the attack, with a paramedic's kit visible in the foreground
‘Officers attended and attempted to speak with a man, who subsequently attacked them.
‘Four officers were injured during the incident and have been taken to hospital.
‘A man has been arrested on suspicion of attempted murder and remains in custody at a north London police station.’
A Metropolitan Police spokesman confirmed to MailOnline that all four officers are in a stable condition.
One sustained a stab wound to the stomach, another sustained head injuries and a stab wound to the arm, a third was wounded in the leg while a fourth suffered a broken hand.
Further down from Kingsbury Halal Butchers on the other side of the roundabout Ketan Vyas, the manager of the VB and Sons cash-and-carry store, described how a man aged 30 to 40 had burst into his shop chased by police.
Shock: The attack happened in broad daylight on a busy shopping street
Stabbing: The area has been sealed off by police, with one man arrested on suspicion of attempted murder
He went on: 'He picked up some cans of beans and threw them at the police and then carried on running out of the store and down the road.
'There were a lot of police after him. He was only in here for a few seconds. Fortunately no staff were harmed.'
Shopkeeper Girish Modha said: 'A man was shouting at police in a small alleyway next to a hairdresser's shop which neighbours mine.
'He grabbed a piece of fluorescent tubing and brandished it at police. He then ran down Kingsbury Road, going into a cash-and-carry shop. At one point I think he threw a brick and smashed a police car window.
'He then ran round the roundabout and carried on towards the Tube station. He went into a butcher's, got a knife and that's when the stabbing took place.'
A worker at a Carphone Warehouse store opposite the butcher's said: 'After the incident I saw about eight police officers on top of a man. Ambulances arrived to take away the injured policemen and the man was also taken away.'
Sky's Martin Brunt tweeted that one of the officers was stabbed in the stomach and that the attacker went 'berserk'.
Eyewitnesses told Bottr that police were called after a man began to attack people 'randomly' .
Brunt added that the suspect had been shouting in the street in 'quite a disturbed way', which led to 999 calls being made.
The Kingsbury Roundabout in north London where the incident happened
Injured: Four police officers have been taken to hospital to be treated for knife wounds, according to Scotland Yard, after being attacked at Kingsbury roundabout
Olympia Logofagul, 24, who works at the Kings Coffee shop on Kingsbury Road, said: 'I was working and I saw some police officers standing outside.
'There were a lot of officers, more than five but no more than 10.'
A spokeswoman for London Ambulance Service said they took five patients to hospital, all conscious and breathing.
She said: 'We were called at 8.50 this morning to an incident in Kingsbury Road.
'We sent two single responders in cars, four ambulance crews and a duty officer.
'We treated five patients, they were all conscious and breathing, and they were taken to hospital.'
Kingsbury Road - a busy thoroughfare in north-west London and normally jammed with shoppers on a Saturday morning - was deserted either side of the roundabout, with police having blocked off the road in both directions.
The hairdressers, Mr Modha's sweet shop and a chemist were cordoned off.
There are 30 police cars and 15 ambulances attended
