About 500 people participate in a simulated "anti-terrorist" operation organised by the Catalan Government at Barcelona's Sants station. The exercise tests the security and emergency forces' response by simulating an attack with multiple people pretending to be injured or dead. Students of health and security-related subjects participate in the simulation as extras. More than 170 members of the Mossos d'Esquadra, the Catalan police, also take part in the exercise. IMAGES AND SOUNDBITES