Seven Birmingham terror suspects arrested as Westminster attacker named as West Midlands man Khalid Masood

• UPDATE: Another West Midlands terror suspect arrested as killer's birth name revealed

• MORE: Who was killer Khalid Masood?

• MORE: 'Oh my God it's him' -Neighbours of Westminster terrorist stunned by atrocity

• MORE: Birmingham vigil planned after thousands pay tribute in Trafalgar Square

• MORE: Thursday's live coverage from our reporters in Birmingham and London

• WRAP: Eight arrests made after overnight raids as ISIS claims responsibility

• MORE: Hagley Road residents describe dramatic armed terror raid

• MORE: Tributes paid after victims named as policeman, mother and tourist

The suspects were held in raids at three addresses in Birmingham, the city where 52-year-old convicted criminal Masood had most recently been living.

Five men and two women were detained as police hunted for accomplices of Masood in Birmingham, while another woman was arrested during a raid in east London.

Meanwhile a fourth victim, a 75-year-old man, died in hospital when his life support was turned off on Thursday evening, the Metropolitan Police said.

As police and intelligence agencies mounted a massive investigation to piece together the killer's movements in the lead-up to the attack:

• Searches were carried out at three addresses in Birmingham and one each in east London, Brighton, south east London and Carmarthenshire

• A 21-year-old woman and a 23-year-old man were held at one address in Birmingham

• A 26-year-old woman and three men aged 28, 27 and 26 were arrested at another address in Birmingham

• They were all held overnight while a 58-year-old man was arrested this morning at a third address in Birmingham

• A 39-year-old woman was arrested in east London

• All seven were arrested on suspicion of preparing terrorist acts.

It comes as neighbours of Masood spoke of their shock at learning they had been living near the knife-wielding killer.

Scotland Yard said Masood was not the subject of any current investigations before Wednesday's outrage and there was "no prior intelligence about his intent to mount a terrorist attack".

However, he was known to police and MI5 and had convictions for assaults, including GBH, possession of offensive weapons and public order offences.

Masood was born in Kent on Christmas Day in 1964 and detectives believe he was most recently living in the West Midlands. He was also known by a number of aliases.

One former neighbour, Iwona Romek, speaking in Winson Green, Birmingham, said she could not believe her eyes when she realised the man who had lived near her was the man responsible for the attack.

She said: "Now I'm scared that someone like that was living close to me."

Searches were continuing at Hagley Road, Birmingham, today after armed officers stormed a flat above the Shiraz restaurant at around 11pm last night.

Police were also scouring for evidence in Winson Green, while it emerged that the car driven by the attacker had been hired from Enterprise in Spring Hill.

There was also visible police presence at an address in the Olympic Park in Stratford, east London.

Three people were killed when the knife-wielding attacker ploughed a car through pedestrians on Westminster Bridge, before storming the Parliamentary estate. He was shot dead. A fourth person died in hospital on Thursday evening.

A day later crowds gathered in Trafalgar Square for a candlelit vigil in memory of the victims.

They heard London Mayor Sadiq Khan praise the bravery of the emergency services responding to the attack.

He said: "When Londoners face adversity we always pull together. We stand up for our values and we show the world we are the greatest city in the world."

Home Secretary Amber Rudd defended the security and intelligence agencies, saying: "The fact that he was known to them doesn't mean that somebody has 24-hour cover."

She revealed Masood had spent time in jail, but said it was not for terrorist-related offences.

Meanwhile the identities of three of the terrorist's victims on Westminster Bridge have emerged, one a US tourist from Utah celebrating his wedding anniversary, the other a "highly regarded and loved" member of college staff.

Kurt Cochran and his wife, Melissa, on the last day of a trip celebrating their 25th anniversary, were visiting her parents, who are serving as Mormon missionaries in London. Mrs Cochran was badly injured.

Aysha Frade, who worked in administration at independent sixth-form school DLD College London, in Westminster, is understood to have been 43 and married with two daughters.

Earlier, Islamic State made its first public pronouncement since the atrocity, claiming in a statement: "The attacker yesterday in front of the British Parliament in London was a soldier of the Islamic State executing the operation in response to calls to target citizens of coalition nations."

Commentators pointed out the terror group has a record of opportunistically claiming attacks and said it was significant the statement did not appear to claim it had directed the strike.

Forty other people were injured in the attack, with 29 treated in hospital, where seven remained in a critical condition on Thursday.

Five people remained in a critical condition on Thursday evening, two with life-threatening injuries.

The casualties included 12 Britons, three French children, two Romanians, four South Koreans, two Greeks, and one each from Germany, Poland, Ireland, China, Italy and the United States.

Three police officers were also hurt, two of them seriously.