Recording the evidence

"There's a danger of being desensitised. We shouldn't dismiss any of them as routine," says Kathleen Kennedy Manzo, the news organisation's managing editor.

"You have to stop and think this is a big event."
Since the beginning of 2018, there have 63 dead or injured in school shootings, according to the tracker's latest figures.

They have almost all been committed by teenagers or young adults, often with links to the school.

After the Parkland killings, there has been a high profile "Never Again" campaign by students calling for action to prevent such attacks - and to prevent such a regular loss of life ever seeming "normal".