A fourth victim has died following the terrorist attack in Westminster on Wednesday (March 22) .

Leslie Rhodes, 75, from Streatham in south London, died in hospital from his injuries on Thursday night.

The attacker, who died after being shot outside Parliament, has been identified by police as Khalid Masood - born Adrian Russel Ajao.

Acting Deputy Commissioner Mark Rowley said on Friday the terrorist "had a number of aliases".

"We remain keen to hear from anyone who knew Khalid Masood well, understands who his associates were and can provide us with information about places he has recently visited," he said.

"There might well be people out there who did have concerns about Masood but weren't sure or didn't feel comfortable for whatever reason in passing information to us."

LONDON, ENGLAND - MARCH 23: People gather during a candlelit vigil at Trafalgar Square on March 23, 2017 in London, England. Four People were killed in Westminster, London, yesterday in a terrorist attack by "lone wolf" killer Khalid Masood,52. Three of the victims have been named as PC Keith Palmer, US tourist Kurt Cochran from Utah and Mother of two Aysha Frade
People gather during a candlelit vigil at Trafalgar Square

The other victims to die after the attack were PC Keith Palmer, who was stabbed outside Parliament, mother-of-two Aysha Frade and American tourist Kurt Cochran.

A vigil to remember the victims was held in Trafalgar Square on Thursday evening.

A young girl lights a candle

Mr Rowley said: "Last night a true cross section of people came together to stand together to remember - but also to send a message, a strong message, to those inspired by hate and extremism of all persuasions that we will not give in to those who seek to breed discord and fear."

LONDON, ENGLAND - MARCH 23: Members of the public light candles during a candlelit vigil at Trafalgar Square on March 23, 2017 in London, England. Four People were killed in Westminster, London, yesterday in a terrorist attack by "lone wolf" killer Khalid Masood,52. Three of the victims have been named as PC Keith Palmer, US tourist Kurt Cochran from Utah and Mother of two Aysha Frade)
Members of the public light candles

He added: "We are grateful for the continued support of the public and the strong calm response that has been shown, and I know that we will continue to stand together."

Contact the Anti-Terrorist hotline on 0800 789 321 with any information.