Expand / Contract FILE- In this March 22, 2017 file photo, the attacker Khalid Masood is treated by emergency services outside the Houses of Parliament London. PHOTOS: AFTERMATH OF 'TERROR INCIDENT' NEAR PARLIAMENTPolice said there was no prior knowledge about his intention to mount a terrorist attack. Masood continued his attack, fatally stabbing veteran police officer Keith Palmer on the Parliament’s grounds before police shot him. Britain's Foreign Secretary Boris Johnson says the fact that victims from the London attack came from 11 countries shows that "an attack on London is an attack on the world." Just this weekend, hundreds of armed police took part in an exercise simulating a "marauding" terrorist attack on the River Thames.

Source: Fox News March 23, 2017 15:38 UTC