Katie Cornelis, from Connecticut, said she gave the doorstops to her two nieces

A woman's poignant Facebook post advising parents to give children doorstops so they can obstruct shooters at school has gone viral in the wake of the Florida massacre.

Katie Cornelis, from Connecticut, said she handed out the doorstops to her two nieces after 27 people - mostly children - were slaughtered at Sandy Hook Elementary School in 2012.

She said that, 'in light of the recent shooting', she wanted to 'share this with all parents' - adding that she 'always' carries hers in her purse.

Cornelis added: '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.

'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.'

She also said she was 'really sad' to be posting the advice, but stressed: 'A security expert shared this tip with me so I wanted to pass it on.'

'I pray no one ever has to use it,' she added.

Speaking to DailyMail.com on Tuesday, she explained her nieces Haley, now 17, and Gabby Bates, 19, lived in Sandy Hook shortly before the massacre.

'They could have been in that school but they moved,' she said. She explained the younger niece was in tears when she was presented with the doorstop, but the Gabby was more 'stoic'.

'After the last shooting I was just so upset and angry,' she added.

Cornelis poses with her two nieces with the doorstops she gave them to take into school after the Sandy Hook shooting in 2012

She said that, 'in light of the recent shooting', she wanted to 'share this with all parents' - adding that she 'always' carries hers in her purse

She said that, 'in light of the recent shooting', she wanted to 'share this with all parents' - adding that she 'always' carries hers in her purse

Cornelis (pictured) added: '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'

The post - written one day after the Stoneman Douglas High School shooting - has so far been shared by over 1.3 million people.

Among those commenting on the post were many people expressing gratitude, including one who wrote: 'This is the right kind of message to go viral right now'.

Another explained: 'Katie can’t believe I’m seeing this shared by some of my friends now. Great advice. Thanks for the post.'

It comes after an anonymous law enforcement source said the Valentine's Day mass shooter, 19-year-old Nikolas Cruz, had bought seven of his ten guns legally in the build-up to the massacre.

He has been charged with 17 acts of murder after the tragedy at Stoneman Douglas High School in Florida.

Nikolas Cruz (left), who has been charged with 17 counts of murder after the slaughter at Marjory Stoneman Douglas High School on Valentine's Day, owned an assortment of shotguns and other firearms as well as the rifles. Right: An Instagram post on Cruz's account showing a rifle

The 19-year-old accused of murdering 17 people in a Florida high school last week had at least seven legally acquired long guns. Pictured: A post on Nikolas Cruz's Instagram showing his weapons stash