Four people have died including a police officer and the attacker in the Westminster terror attack.
Among them was an armed police officer, who has not yet been named, and was stabbed by the attacker outside Parliament.
The other people are believed to have died on Westminster Bridge.
Scotland Yard's top anti-terror officer Mark Rowley confirmed four people dead and at least 20 other people injured.
Emergency services were called to Westminster Bridge at around 2.40pm.
A car drove over Westminster Bridge hitting and injuring members of the public and police officers before it crashed through the gates of the Palace of Westminster and the attacker ran in and stabbed a police officer.
Acting deputy commissioner Mr Rowley said: “Sadly, I can confirm that four people have died including one police officer.
"The attack today injured a number of members of the public including 3 police officers protecting Parliament.
“Our strength as a city is our ability to stand together. We will do all we can to protect the people of London.
“We're carrying out a full scale investigation into the events today in Westminster."
A crime scene will remain in place while a full counter terrorism investigation is under way.
Keep up to date with the latest news in west London via the free getwestlondon app.
You can even set it to receive push notifications for all the breaking news in your area.