Solidarity pledged as Europe tightens security

World leaders have responded to the deadly attacks in Paris with defiant pledges of solidarity.

Security measures have also been intensified across Europe after the Islamic State group said it was behind the attacks by gunmen and bombers on Friday that left at least 129 dead in the French capital.

Heads of state worldwide expressed their condolences to French President Francois Hollande, who said the attacks amounted to an act of war against his country.