Two pedestrians, one police officer, the perpetrator of a terrorist act and a yet unidentified person are dead following a horrific attack outside the Houses of Parliament Wednesday afternoon.

At around 2:40 p.m., a man, who the police have now said is “known” to them, drove a grey-coloured 4x4 Hyundai i40 car at speed over Westminster Bridge, near the Houses of Parliament. It mounted the pavement, leaving around 20 casualties lying on the bridge, veering across a cycle lane before crashing into parliament’s perimeter fencing surrounding New Palace Yard. One woman died on the bridge.

The assailant, who appeared to be in his 40s and dressed in black, jumped out of the car and proceeded to sprint through the New Palace Yard gates. He was reportedly armed with two knives including one with an eight-inch blade. When police officers confronted him, he stabbed a plain-clothes officer repeatedly before turning towards a second officer. He was shot several times and later died of his injuries. The stabbed officer, PC Keith Palmer, died of his wounds.

The first doctor on the scene was Dr Jeeves Wijesuriya, the current chairman of the junior doctors' committee at the British Medical Association. He tried unsuccessfully to resuscitate both the police officer and the assailant, the latter for almost an hour, as well as attending to other injured people at the scene.

The London Ambulance Service said paramedics had treated at least 10 people on the bridge.

Among the victims of the terror attack are three French schoolchildren on a school trip as well as students from the northwest of England. At least two of the teenage pupils from a private high school in Concarneau are in critical condition. Their families have been flown by a military plane to London.

It is unclear whether other reports of two people in critical condition are in addition to the pupils. Initial reports spoke of people suffering “catastrophic injuries.”

A woman who fell into the Thames was rescued and given emergency treatment on the spot. The Port of London Authority reported that her injuries were serious and other reports speak of her being in a critical condition.

The Guardian reports witness Steve Voake, 55, seeing at least two bodies in the road and “when he looked over the side of the bridge ‘there was another body lying in the water with blood all around it’.”

Bus driver Michael Amadou described how the attacker had “started from the hospital heading towards parliament and just mowed down whoever was in his way... I heard one guy come running behind me shouting his wife had jumped into the river to avoid getting knocked down.”

Three police officers were also among those injured on the bridge.

A total of five London hospitals treated 12 casualties with serious injuries. Eight people, six males and two females, have been treated at King’s College Hospital. Two are reportedly in a stable condition at St Thomas' Hospital, which is adjacent to Westminster Bridge. The Daily Telegraph reports that the two were identified as Romanian tourists Andrei and Andrea, both in their late 20s, by their friend, Patrick Tracey.

Police locked down the area in the event reports of a second attacker proved to be true, but later confirmed that the assailant was believed to have acted alone. Additional police were put in place in the vicinity and throughout the capital. Parliament was in session and MPs were kept under lockdown until 7:45 p.m. During the morning hours raids and seven arrests were made—mostly in London and Birmingham.

The Scottish parliament at Holyrood suspended a two-day debate on whether to seek permission from the UK government for the required section 30 order to hold a legally-binding referendum on independence. The suspension was demanded by Conservative MSPs, including Scottish leader Ruth Davidson.

As could be expected, the ruling elite in Britain and internationally were quick to make political capital from the appalling event; above all to justify the repressive domestic measures that have accompanied the colonial-style wars in the Middle East and North Africa, which have played the major role in fostering the growth of Islamist terrorism.

Conservative Prime Minister Theresa May struck a Churchillian pose while reporting from a meeting of COBRA, the emergency committee made up of ministers and senior security and intelligence officials that have now spent decades plotting to curtail or eliminate fundamental democratic rights.

“The terrorists chose to strike at the heart of our Capital City, where people of all nationalities, religions and cultures come together to celebrate the values of liberty, democracy and freedom of speech,” she declared. “These streets of Westminster—home to the world’s oldest Parliament—are engrained with a spirit of freedom that echoes in some of the furthest corners of the globe. And the values our Parliament represents—democracy, freedom, human rights, the rule of law—command the admiration and respect of free people everywhere.”

This is said of a parliament that has supported illegal wars in Iraq, Afghanistan, Libya and Syria, and which has passed legislation collectively representing a frontal assault on free speech, liberty and the rule of law without precedent in British history.

French President Francois Hollande, who rules—at least for a few more weeks—over a nation subjected to a semi-permanent state of emergency with vast numbers of armed police on the streets stated, “France knows how the people of Britain are suffering today”—a reference in particular to last July’s incident, where a man well-known to the police and security services drove a lorry into pedestrians in the city of Nice, killing 84.

German Chancellor Angela Merkel, for her part, pledged to “stand firmly and resolutely by Great Britain's side in the fight against all forms of terrorism." In December, a similar attack on a Christmas market killed 12 people in Berlin.

US President Donald Trump offered May his condolences by telephone, while White House spokesman Sean Spicer told reporters, “Her Majesty's government have the full support of the US government in responding to the attack and bringing those to justice who are responsible.” In New York City, armed police officers and bomb-sniffing dogs were deployed to the British Consulate, the British Mission to the United Nations, City Hall and the Grand Central Terminal.