A woman holds a placard that reads, "I am Charlie", during a vigil to pay tribute to the victims of a shooting by gunmen at the offices of weekly satirical magazine Charlie Hebdo in Paris, at Trafalgar Square in London on January 7, 2015. Gunmen stormed the Paris office of the magazine, renowned for lampooning radical Islam, killing at least 12, including two officials, in the worst militant attack on French soil in recent years. [Photo/Agencies]