In the US in 2015, more people were shot and killed by toddlers than by terrorists.
The Guardian article refers readers to a long, in-depth article in the NY Times from 2013. You really should click over and read it, even if you are pooh-poohing the entire premise here because of your strong belief in your 2nd Amendment rights:
A New York Times review of hundreds of child firearm deaths found that accidental shootings occurred roughly twice as often as the records indicate, because of idiosyncrasies in how such deaths are classified by the authorities. The killings of Lucas, Cassie and Alex, for instance, were not recorded as accidents. Nor were more than half of the 259 accidental firearm deaths of children under age 15 identified by The Times in eight states where records were available.
As a result, scores of accidental killings are not reflected in the official statistics that have framed the debate over how to protect children from guns.
But maybe we need to hold adults more responsible for securing weapons?
In all, fewer than 20 states have enacted laws to hold adults criminally liable if they fail to store guns safely, enabling children to access them.
The bottom line?
Children shot accidentally – usually by other children – are collateral casualties of the accessibility of guns in America, their deaths all the more devastating for being eminently preventable.