Families of children killed in the Sandy Hook mass shooting have released a chilling video showing pupils using back to school "essentials" to save them from a gunman.

At first, the public service announcement, called "Back to School Essentials", looks like a typical clip of students gathering every day school items such as backpacks and folders as they return after the summer holidays.

Smiling children show off their new purchases, but it quickly becomes clear they are showing how every day items can be used to escape from a school shooter.

The video has been released by Sandy Hook Promise, a non-profit organisation led by family members of children killed at Sandy Hook elementary school in Connecticut in 2012.

Image: A girl is seen writing a text to her mum as the gunman enters the bathroom she is hiding in

Adam Lanza, 20, shot and killed 20 children aged six and seven, and six members of staff, after killing his mother then turning the gun on himself.


The video racked up more than 400,000 views within hours of being released on Wednesday.

It includes a boy using his new skateboard to smash windows so children can escape, a girl using her sock as a tourniquet on a bleeding student, and pupils in an art class getting ready to approach the gunman with scissors and colouring pencils.

Image: 20 children and six staff were shot dead at Sandy Hook elementary in 2012

A student running down a hallway while others scream behind him says: "These new sneakers are just what I needed for the new year."

The final clip is the most harrowing, showing a girl hiding in a bathroom cubicle as she texts her mum an "I love you mom" message.

"I finally got my own phone to stay in touch with my mum," she says with tears rolling down her face, as a door creaks open and footsteps are heard.

The advertisement ends with a black screen and the words: "It's back to school time and you know what that means.

"School shootings are preventable when you know the signs."

The advertisement is part of Sandy Hook Promise's school violence prevention programme "Know the Signs", which teaches pupils and adults how to recognise warnings signs and intervene to prevent mass shootings.

Managing director of the non-profit, Nicole Hockley, whose six-year-old son Dylan was killed in the shooting, told CNN: "We wanted to focus on this back-to-school time because parents still think of it as this rosy time where you're getting your staplers, shoes, folders and binders.

"Whereas, it's back to a time of violence for a lot of kids."

Image: A vigil on the third anniversary of the Sandy Hook school shooting

In the seven years since the Sandy Hook shooting there have been 387 school shootings, and nearly 20 in the past year, according to the Center for Homeland Defense and Security.

Last year was the worst on record, with 97 incidents, including the deaths of 17 children and staff at Marjory Stoneman Douglas High School in Parkland, Florida, after expelled student Nikolas Cruz opened fire with an AR-15-style semi-automatic rifle.

The video has been released days after the Democrats applied pressure on the US Senate to vote on a bill which would require background checks for all gun sales.

Another bill would strengthen background check procedures on gun retailers.

Both were passed by the House more than six months ago but it remains to be seen what President Donald Trump's stance is.