British Police on watch after a terror attack in London, March 22.

The death toll from the terror attack on the UK Parliament claimed by Islamic State has risen to five as Scotland Yard confirmed that a fourth victim has died of injuries in an hospital. The Islamic State, March 23, claimed responsibility for the brazen terror attack on the UK Parliament that killed five people, including the British-born attacker who was known to British secret services, even as eight people were arrested in raids across London and Birmingham, reports Aditi Sharma. – @Siliconeer #Siliconeer #UK #LondonTerrorAttack #ISIS #TheresaMay #ScotlandYard

A spokesperson for King’s College Hospital in south London confirmed that the 75-year-old man had been treated there prior to his death.

A Scotland Yard spokesperson said: “Detectives investigating the terrorist attack in Westminster on March 22, can confirm that the man died, March 23.

“The man had been receiving medical treatment in hospital following the attack and life support was withdrawn (March 23) evening. Next of kin have been informed and are receiving support from specially trained family liaison officers,” the spokesperson said.

The man has not yet been named.

Two people, American Kurt Cochran and Spaniard Aysha Frade, were also killed and about 40 others were injured when the 52-year-old attacker, identified as Khalid Masood, mowed down pedestrians on a bridge and stabbed to death a police officer outside parliament complex in the heart of Westminster before being shot dead by Scotland Yard.

Masood, who was born in Kent and had previously been convicted of violent offences, had been known to MI5 but was considered to be a peripheral figure. He was known by a number of aliases and had been living in the West Midlands recently.

Prime Minister Theresa May had said the attacker was British born and he was once investigated in relation to concerns about violent extremism few years ago.

The ISIS on its propaganda news agency ‘Amaq’ had claimed responsibility, saying a “Soldier of the Caliphate” carried out the attack on the British Parliament.

“The operation was carried out in response to calls to target coalition countries,” it said in a statement.

Eight people have been arrested during raids across London and Birmingham following the attack on the Palace of Westminster in London, which houses Britain’s Parliament and the iconic Big Ben.

In a message to the police, British Queen Elizabeth II said, “My thoughts, prayers and deepest sympathy are with all those who have been affected by the awful violence.”

Among 40 injured, 29 were admitted to hospital including 12 Britons, three French children, two Romanians, four South Koreans, one German, one Pole, one Irish, one Chinese, one Italian, one American and two Greeks.

Girls pay tribute to London terror attack victims with a painting, in Mumbai, March 23. (Santosh Hirlekar/PTI)

“We are not afraid…An act of terrorism tried to silence our democracy, but today we meet as normal,” May told sombre-looking lawmakers in the packed House of Commons which reopened, March 23, with a minute’s silence a day after the attack.

Police said Masood had previous convictions for a number of violent offences. He was arrested in the past for causing grievous bodily harm, but not in relation to terror charges.

His first conviction was in 1983 for criminal damage and his last conviction was in December 2003 for possession of a knife, Metropolitan Police said.

“Masood was not the subject of any current investigations and there was no prior intelligence about his intent to mount a terrorist attack. However, he was known to police and has a range of previous convictions for assaults, including GBH, possession of offensive weapons and public order offences,” a Scotland Yard statement said.

May said the threat level to the UK has been set at ‘severe’ meaning an attack is highly likely for some time. This is the second highest threat level. The highest level ‘critical’ means there is specific intelligence that an attack is imminent.

Giving details known about the attack, May said a single attacker drove his vehicle at speed into innocent pedestrians who were crossing Westminster Bridge, killing two people and injuring around 40 more, of which 29 were hospitalized.

The attacker then left the vehicle and approached a police officer at Carriage Gates of Parliament, attacking him with a large knife, before he was shot dead by an officer.

“There was no prior intelligence of attacker’s intent or of the plot. Intensive investigations continue,” May said.

She also paid tribute to the security services and the police officer who lost his life in the attack.

Scotland Yard Acting Deputy Commissioner and Head of Counter Terrorism Mark Rowley urged the public to use their instincts and report anything suspicious, saying the Met Police will be working round the clock and all annual leave has been canceled.

“We must not allow terrorists to create discord, distrust and fear. The police stand with all communities,” Rowley said.

West Midland Police officers stormed a second-floor flat in the city believed to be the residence of the knife-wielding attacker and led away people in handcuffs.

It has also emerged that the car used in the attack was reportedly hired from Solihull area of Birmingham.

The flag at New Scotland Yard premises in London is flying at half-mast following the attack, which claimed the life of one of their officers who was on guard at Parliament.

Mayor of London Sadiq Khan invited all Londoners and visitors to the capital to a candlelit vigil in Trafalgar Square to show solidarity with the victims of the attack.