The Westminster terror attack has claimed its fourth innocent victim, as police confirmed that a 75-year-old man has died in hospital.

A Scotland Yard spokesman said: "The man had been receiving medical treatment in hospital following the attack and life support was withdrawn this evening.

"Next of kin have been informed and are receiving support from specially trained family liaison officers."

The attacker who brought terror to the streets of the capital has been named as Khalid Masood and detectives investigating Wednesday's attacks on Westminster Bridge and at the Houses of Parliament said they had arrested three women and five men on suspicion of preparing terrorist acts.

The suspects were held in raids in London and Birmingham as neighbours of Masood, a 52-year-old with a string of criminal convictions including possession of a knife, spoke of their shock.

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.

Unarmed Pc Keith Palmer died after being stabbed at the Houses of Parliament.

The Westminster Bridge victims include a US tourist from Utah who was celebrating his wedding anniversary and 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.