The Prime Minister said it was “no accident” the terrorist struck “in the heart of our capital” and paid tribute to the victims, including a policeman who was stabbed to death by the knife-wielding terrorist.
Cops outside Parliament after an attacker stabbed a cop after storming the gatesTheresa May, who was bundled into a silver Jaguar and rushed from the scene earlier, said: "The terrorist chose to strike at the heart of our capital city.
“The values our parliament represents - democracy, freedom, human rights, the rule of law - command the admiration and respect of free people everywhere.
“That is why it is a target for those who reject those values.”
She added: "Tomorrow morning, Parliament will meet as normal. We will come together as normal.And Londoners - and others from around the world who have come here to visit this great City - will get up and go about their day as normal.
"They will board their trains, they will leave their hotels, they will walk these streets, they will live their lives. And we will all move forward together. Never giving in to terror. And never allowing the voices of hate and evil to drive us apart."
Twenty were injured in the attack, including three police officers and at least four students.
Two people are now fighting for their lives and 10 others are seriously injured, London Ambulance Service said.
Pictures of a man believed to be the suspect have emerged showing a blade lying on the cobbled street next to him.
A Met police spokesman warned Londoners to be wary of copycat attacks, saying it would be "foolish" to dismiss the event as "over".
They added: “We have lost one of our own as he acted to protect the public. This is a day we planned for but hoped would never happen. Sadly it is now a reality.”
Paramedics were seen tending to the attacker as armed cops trained their rifles on his stripped body outside Parliament.
Other dramatic pictures show the bloodied bodies of victims littering Westminster bridge as heroic bystanders desperately try to save the lives of those "catastrophically" injured.