Tributes have been paid to Police Constable Keith Palmer, school administrator Aysha Frade and American tourist Kurt Cochran, who were among the victims of a terror attack in London yesterday.
This evening a 75-year-old man who was injured died in hospital, becoming the fourth victim of the attack.
The bravery of murdered PC Palmer has been praised by colleagues, friends and the many MPs whom he was charged with protecting.
Ms Frade, 43, was the first member of the public to be identified as a victim, with her principal at DLD College London describing her as "highly regarded and loved".
Ms Frade is understood to have been married with two daughters. According to reports Ms Frade had left work and was crossing Westminster Bridge as part of her usual routine when she was hit by a car.
She died along with PC Palmer and Mr Cochran after a knife-wielding attacker ploughed a car through pedestrians on the bridge, before storming the Parliamentary estate.
He was shot dead by police.
"Heartbroken" former colleague of PC Palmer, Conservative MP James Cleverly, paid tribute to the "lovely man" he had known for a quarter of a century.
He wrote of the 48-year-old father and husband: "I've known Keith for 25 years. We served together in the Royal Artillery before he became a copper.
"A lovely man, a friend. I'm heartbroken.
"My thoughts are with the family, friends and colleagues of PC Keith Palmer. A brave man."
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Mr Cochran was in Europe with his wife Melissa to celebrate their 25th wedding anniversary. She was also seriously injured in the attack.
"My sister, Melissa, has a broken leg, a broken rib, and a cut on her head," Sara Payne-McFarland wrote on Facebook.
A great American, Kurt Cochran, was killed in the London terror attack. My prayers and condolences are with his family and friends.
— Donald J. Trump (@realDonaldTrump) March 23, 2017
"While we are glad she survived, our hearts are broken and will never be the same after losing our dear uncle, brother-in-law, father. Kurt, you are a hero, and we will never forget you."
Scotland Yard's top anti-terror officer Mark Rowley said of his colleague, PC Palmer: "He was someone who left for work today expecting to return home at the end of his shift - and he had every right to expect that would happen."
Greater Manchester Police chief constable Ian Hopkins added: "#RIP PC Keith Palmer, brutally murdered today carrying out his duty helping to protect Parliament and the freedom of our Country."
The Metropolitan Police Federation, which represents officers from the force, said: "PC Keith Palmer. Our brave Met #Police colleague who today made the ultimate sacrifice #LestWeForget"
A chorus of thanks also came from politicians on all sides of the House.
Home Affairs Select Committee chairwoman Yvette Cooper, who was in the Palace of Westminster when the terrorist burst through the gates, said: "Thank you PC Keith Palmer - to your bravery many others owe their lives and safety"
Labour MP Barry Gardiner was also caught up in the lockdown and posted a picture of armed police moving through Parliament.
He tweeted: "Going to bed alive, safe and well thanks to PC Keith Palmer. God bless him, his family and all those killed or injured. Terror will not win."
Geoffrey Cox, Conservative MP, wrote: "Deeply sad that a brave PC, Keith Palmer, died in the service of his country, doing his duty today. We should be proud to know such men."
MP Chi Onwurah tweeted: "As I left Parliament a police officer apologised for keeping us waiting. Cannot overstate courage & grace of those who protect us Thank you."
One woman who said she had her life saved by PC Palmer when she worked as a police officer paid tribute to the "absolutely lovely man".
Giving her name only as Nina, from Orpington, south-east London, she told radio station LBC: "He actually did save my life in a car accident on duty, I was a police officer.
"I was a police officer at the time, in 2007.
"I had a car accident on duty, I was the passenger. I was the passenger and he was one of the police officers who actually saved my life.
"I owe him everything. He was a wonderful dad, and wonderful husband to his wife and everything."
Reflecting on the officer's attitude to his work, she said: "He didn't just do his job to go and get paid. He actually cared about the people.
"He really did, he was a lovely man, absolutely lovely man, and everyone's going to really miss him."
Shock and sadness at death of school administrator
Ms Frade was "a highly regarded and loved" member of staff at the London sixth form college where she worked.
She worked in the administration team at DLD College London, just a few hundred metres from Westminster Bridge, principal Rachel Borland confirmed this morning.
Ms Borland said: "We are all deeply shocked and saddened at the news that one of the victims yesterday was a member of our staff, Aysha Frade.
"All our thoughts and our deepest sympathies are with her family.
"We will be offering every support we can to them as they try to come to terms with their devastating loss.
"Aysha worked as a member of our administration team at the college. She was highly regarded and loved by our students and by her colleagues. She will be deeply missed by all of us."
