A new ad shows students using their new school supplies during a school shooting.
The final scene of a new advertisement designed to raise awareness to prevent school shootings is so confronting even its creators find it hard to watch.
Sandy Hook Promise, an organisation founded by the parents of children who died in the Sandy Hook Elementary School shooting in 2012, has released its latest back-to-school ad.
The "public service announcement" shows students showing off their brand new school supplies before demonstrating how they can be put to use in the event of a shooting.
One boy runs down the corridor in his new sneakers dodging bodies, while others hold coloured pencils and scissors at the ready to use in defence.
But it's the final scene that really packs a punch.
"At the end, the girl with the phone gets me every time," Sandy Hook Promise co-founder Nicole Hockley told US talk show Today.
At the end of the advertisement, a girl hiding in the bathroom uses her new phone to text "I love you" to her mother.
"We don’t want people to turn away from it, so pretending it doesn’t exist is not going to solve it."
Ms Hockley's six-year-old son Dylan was among 20 children and six adults that were killed in the December 2012 shooting.
She said the advertisement is part of a "Know The Signs" campaign to help train teachers and peers to identify troubling behaviour and intervene before they escalate to violence.
"I will never put a bulletproof backpack on my kid,” Mr Hockley said on Today. “I think it sends totally the wrong message: He’s not a soldier going off to war; he’s a boy going off to math class."
An analysis by The Washington Post shows more than 228,000 students have experienced gun violence at school since the Columbine shooting in 1999.