A look at some past notable extremist attacks in Western Europe:
— Jan. 7, 2015: A gun assault on the Paris offices of satirical magazine Charlie Hebdo kills 12 people. Al-Qaeda in the Arabian Peninsula claimed responsibility for the attack, saying it was revenge for Charlie Hebdo's depictions of the Prophet Mohammed.
— May 24, 2014: Four people are killed at the Jewish Museum in Brussels by an intruder with a Kalashnikov. The accused is a former French fighter linked to the Islamic State group in Syria.
— May 22, 2013: Two al-Qaida inspired extremists run down British soldier Lee Rigby in a London street, then stab and hack him to death.