European Officials Step Up Security Measures in Wake of Paris Shooting

Several European countries stepped up security measures as Wednesday’s shooting in Paris reinforced long-held worries among officials about the threat of gun-wielding attackers.

European security and intelligence officials say people who act alone or in small groups and sow carnage with guns are among the biggest threats to emerge from the current wave of Islamic extremism. That is because they are easier to organize than a large-scale bombing plot and will typically involve less communication within terror networks that intelligence agents can intercept.