>> Four people killed, around 40 injured. And police raids taking place across the country. I'm Reuters' Jacob Greaves reporting from Westminster, now the scene of the bloodiest attack on British soil July 2005. The very latest police briefing we're hearing said there's been seven arrests made across six addresses.
It's focused around Birmingham and London, with police continuing to investigate Wednesday's events. They say they believe to know the identity of the attacker, but haven't yet made that information public. They do, however, stress they think he acted alone, inspired by international terrorism. We're getting an increasingly detailed picture of the events on Wednesday afternoon.
As the attacker in a vehicle careened across Westminster Bridge, knocking down bystanders before slamming into the perimeter fence of the Houses of Parliament, getting out of his vehicle and trying to breach security. There he is confronted by a policeman who he stabbed to death before armed police responders shot the perpetrator.
The perpetrator later dying in hospital. I spoke to a Labour MP who was on lockdown in Parliament during the attack.>> I don't think anybody's surprised. Everybody's shocked, but I don't think anybody's surprised because in a sense a marauding attack of this nature was one of our biggest fears for a very long time.
I mean maybe there will have to be reviews, well, there's always a constant review of our security arrangements. And I'm sure there will be another one on the back of this.>> Numerous people are still said to be in a critical condition. But much the attention is shifting to who the attacker was, what were his motives?
The scene behind me is still cordoned off. Westminster, the heart of British politics, is for the moment a crime scene.