Aunt's "great" advice for kids facing school shootings in the US is, frankly, depressing.

A woman has shared a ‘handy hint’ for an item to keep in kids’ backpacks in case of a school shooting. Only in America could this go viral.

A day after 17 people were gunned down in a Florida high school on 14 February, Connecticut woman Katie Cornelis shared in a Facebook post the one item she insisted her nieces “always keep in their backpacks” – a doorstop.

Cornelis said the item could be life-saving in the event it’s used to keep a door from being opened by a gun-wielding person on a rampage. She said the doorstops became essentials for her nieces after Connecticut’s Sandy Hook Elementary School massacre in 2012.

LISTEN: Podcast host Amelia Lester explains why US gun laws will never change, no matter how many lives are lost. (Post continues.)

“It truly pained me when I handed it to them, and I didn’t want to scare them, but it was out of love and they understood,” Cornelis wrote in the Facebook post.

After sharing the rest of the nation and the world’s horror at yet another mass shooting, she decided to offer the tip.

“I wanted to share this with all parents…and ANYONE else for that matter…to get themselves [a doorstop] (I always carry mine in my purse).”

“Sure it’s small, but it can be powerful in keeping you safe if you ever have to barricade yourself in a room.

“If a gunman shoots out the door lock it will still keep the door from opening and may just buy you some time.”

Cornelis said the tip came to her via a security expert.

“I pray no one ever has to use it,” she wrote.

In less than a week her post has been shared more than 1.3 million times, with many commenting it was “great advice.”

It’s a chilling reminder of how common gun violence and mass shootings are in the US.

Nineteen-year-old Nikolas Cruz’s murder of 17 former classmates and school staff at Marjory Stoneman Douglas High in Parklands, Florida was the 18th mass shooting in the US so far this year.