Schoolgirl 'expert' advises how to survive a shooting in powerful PSA

Following the 20-year anniversary of the Columbine high school shooting, March For Our Lives has released a brilliant but hard-to-watch PSA, revealing how US schools and students have had to respond to the increasing threat of gun violence across the country.

The fly-on-the-wall video - created by McCann New York and directed by Bryan Buckley via Hungry Man - opens on a company team-building exercise, where an expert has been invited in to provide advice on what to do in an active shooter situation. Try and protect your friends by pushing the chairs and tables against the doors; if you're in the bathroom, stand on the toilet seat and crouch down so your feet and head are hidden; and above all, don't cry: it gives away your hiding spot are among her tips for survival - intercut with heartbreaking images from actual shooting scenes, protests and memorials. 

The most horrifying aspect? The 'expert' is a young schoolgirl clad in dungarees - and she's passing on the training that has been drilled into her, as it has for 95% of 'Generation Lockdown' school kids, some as young as five, because they have to be prepared a shooting at any minute, in any community. The video closes with a call for viewers to support federal legislation to put universal background checks in place for the purchase of firearms. Properly powerful stuff.