Those caught up in the Westminster attack include a party of French schoolchildren who were struck on the bridge.

Four students from Edge Hill University in Lancashire were also hurt. Two were described as "walking wounded" and the others were said to have minor injuries. 

Romanian and South Korean tourists were also affected.

London's transport authorities are advising early morning travellers to avoid the Westminster area, warning them that roads there are still closed.

BBC Newsnight reported earlier there was a suggestion the car used in the attack was hired from an address in Birmingham. However, this has not been confirmed.

Londoners have taken to social media to show their defiance after the attack, using hashtags #WeAreNotAfraid and #PrayForLondon.

Users from around the world immediately joined in, voicing their support. 

More details are emerging about the five injured South Korean tourists (see our 23:08 entry).

The foreign ministry in Seoul said they were hurt in a stampede as people tried to flee the area after the attack. 

Three women and one man - in their 50s and 60s - had broken bones, while another woman - in her 60s - had a head injury and needed an operation.

New Zealand's Prime Minister Bill English condemned the London attack. 

He said he had written to Theresa May to express support for Britain. 

Meanwhile, Australian Prime Minister Malcolm Turnbull said: "Australia's heartfelt sympathy and resolute solidarity is with the people of the United Kingdom, with whom we stand today as we always have in freedom's cause. Staunch allies in the war against terrorism." 

Mr Turnbull added that police presence at the Australian Parliament House had been increased. 

US President Donald Trump's son criticised London Mayor Sadiq Khan shortly after the attack in Westminster.

Donald Trump Jr  t, external weeted an article written last year, in which Mr Khan said terror vigilance had become "part and parcel" of life in a global city.

"You have to be kidding me?!" said Mr Trump Jr, immediately sparking accusations that he was exploiting the tragedy and misrepresenting the mayor's point.

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Ron Huldai, the mayor of Tel Aviv, said on Twitter: "#TelAviv City Hall lit up tonight in colours of the Union Jack, in solidarity with the city of #London and my colleague @SadiqKhan"

Image source, Reuters

Police officers from across the UK have been paying tributes to PC Keith Palmer, who died in Wednesday's attack. 

The Metropolitan Police Federation, which represents 30,000 officers in the London area, praised its fallen officer: 

Greater Manchester Chief Constable Ian Hopkins also paid tribute:

The Metropolitan Police have now released the full statement by Mark Rowley, the national lead for Counter Terrorism Policing and Acting Deputy Commissioner. 

British police have trained for an attack like this - but there are some very long hours and days ahead for investigators, writes the BBC's home affairs correspondent Dominic Casciani.

Terrorism seeks not just to kill and maim - but to create panic and such a sense of disorder that it rocks a city or nation to its foundations.

And this attacker sought to do so in as low-tech a way as possible, our correspondent says.

Read more from Dominic

Four people, including a police officer and an attacker, are dead and 40 others have been injured in a terror attack in Westminster.

Flowers have been laid at the scene in Westminster this evening.

Image source, Reuters

Image source, Reuters

Image source, Reuters

Today's attack on Westminster comes just nine months after MP Jo Cox was shot and stabbed to death at a constituency surgery - and her husband Brendan has paid tribute to the victims of today's attack.

And he said in a tweet that the name wants to remember from today's events is PC Keith Palmer - not that of his killer.

Mr Cox, whose wife was stabbed and shot by a right-wing extremist outside her constituency office last June, said the identity of the suspected terrorist was irrelevant.

Sharing a picture of Mr Palmer on his Twitter feed, he wrote: "I don't care about the name of the attacker. This is the name I will remember." 

Scottish Parliament's Presiding Officer Ken Macintosh said in a statement: "No matter how significant our debate might be, to have continued further would not have been appropriate.

"It was increasingly apparent from the chair as reports emerged [from London] that the thoughts and concerns of members lay elsewhere.

"While there is no intelligence to suggest a specific threat to Scotland, Edinburgh or Holyrood, security at the Scottish Parliament has been heightened with immediate effect as a precautionary measure."

Parliamentary business in Edinburgh will proceed as normal on Thursday.

A Holyrood vote expected to back Nicola Sturgeon's calls for a second Scottish independence referendum was put on hold after the terror attack in Westminster.

MSPs were due to vote on whether the Scottish government should seek discussions with the Conservative administration at Westminster on the details of a section 30 order - the legal mechanism that would allow a second independence ballot to be held.

It will now take place at another time to be confirmed.