#WeStandTogether: London unites after Westminster attack
Londoners have shown sympathy and solidarity after the terrorist attack in Westminster.
People took to Twitter using the hashtags #WeStandTogether and #WeAreNotAfraid to show their defiance.
It came as London Mayor Sadiq Khan announced a vigil for the victims at Trafalgar Square at 18:00 GMT.
A minute's silence was also held at 09:33 GMT in memory of PC Keith Palmer. He was one of four people who died in the attack on Wednesday.
The minute's silence was timed for PC Palmer's shoulder number. Surrey Police tweeted images of its officers observing the silence.
And the Metropolitan Police in Hainault, Redbridge, tweeted their appreciation after a lady stopped an officer in the street to offer her sympathies at the death of PC Palmer.
On the streets of central London at lunchtime it was business as usual with crowds of people hurrying along Oxford Street and Regent Street.
One couple on holiday from Lithuania, Valentina and Saulius Nartinis, both 63, said they were unconcerned by what they had seen.
"We were about 100 yards from Big Ben when it [the attack] happened," said Mr Nartinis. "We saw the car crash into the gate [at Parliament]. We didn't know what was going on at first. We were there for about two hours."
"It's quite dangerous but its a big city," said Mrs Nartinis.
Both said there had not been a terrorist incident in Lithuania in 20 years, but what they had witnessed had not put them off going out.
Mr Nartinis added: "In the last five years we have been to Paris, Rome and now London. It's the same in any big city but we're not afraid."
Across social media people wrote messages of support and remembrance. Others invoked the "Blitz spirit" warning potential terrorists the capital had been through worse and survived.
They included one who tweeted: "Dear terrorists. This is the spirit you are trying to break. You won't succeed. Love from us" alongside an image of a woman drinking tea during the Blitz.
Others tweeted messages of support including Sophie Yiannouris who tweeted the message board at Richmond station containing a quote from Transport for London staff which read: "Bad things do happen in the world... But out of those situations arise stories of ordinary people doing extraordinary things."
It was among many messages of defiance, solidarity and support across the London Tube network, which saw the last large scale terrorist attack 12 years ago on 7 July 2005.
Charlton Athletic tweeted that PC Palmer was a season ticket holder and a scarf would remain on his seat in tribute until the next home game on 4 April while the club discusses ways to commemorate his life.
A club spokesman said: "Keith was a familiar face at The Valley to many supporters and sat in his same East Stand seat for many years.
"Keith was a true hero who will be greatly missed by all the Charlton family and everyone at the club would like to offer their sincere condolences to his family and friends at this extremely difficult time."
Several football clubs also tweeted messages of support and remembrance for the victims of the attack on Westminster Bridge. Tottenham Hotspur tweeted: "The thoughts of everyone at the Club are with all those affected by yesterday's incident in Westminster."
Meanwhile, Queens Park Rangers tweeted the "thoughts of everyone at #QPR are with those affected by the atrocities in #Westminster".
Elsewhere, the flag above Lambeth council's offices was shown at half mast as the borough, linked to Westminster by the bridge on which the attack began, remembered those who died.
Despite the attacks many people tweeted how normal a day Thursday was, highlighting how little affect the attacks had had on ordinary Londoners going about their usual business.
Still more expressed their pride at living in a city of diverse people's and cultures including Lily Piachaud who tweeted: "Proud, as I always am, to be a Londoner and live in a city full of kind, tolerant people who respect and value difference #WeAreNotAfraid."