World shows solidarity, tightens security after Paris attacks

World leaders responded to Friday's bloody attacks in Paris with outrage and defiant pledges of solidarity, but several countries said they would tighten security, especially at their borders, and a few urged their citizens not to travel to France. Islamic State claimed responsibility on Saturday for the coordinated assault by gunmen and bombers that killed 127 people across Paris. President Francois Hollande said the attacks amounted to an act of war against France.