Boy , 13 , arrested after deadly shooting at secondary school in Barcelona . The attacker allegedly shot and killed a teacher using a crossbow . Teen had written a ' kill list ' of 25 teachers and students , some say . Two students and two teachers were injured in the shooting this morning . Attack took place on 16th anniversary of secondary school shooting .
Boy , 13 , arrested after deadly attack at secondary school in Barcelona . The teenager allegedly shot and killed a teacher using a crossbow . Teen had written a 'kill list ' of 25 teachers and students , classmates say . Two students and two teachers were injured in the attack this morning . Attack took place on 16th anniversary of Columbine school massacre .