The terrorists who claimed 129 lives Friday night in Paris targeted "youth in all its diversity," said French President Francois Hollande. As the city mourned and searched for reasons behind the inexplicable tragedy, poignant memorials appeared near the places where they died and on Facebook and Twitter. "You left us too young, dying in Paris so far away from us, taking with you your joy of living and so many hopes," said a Facebook tribute to Kheireddine Sahbi, 29, an Algerian violinist. Associated Press photos