Anytime one of these types of shootings occurs, you can guarantee that there'll be a lot of articles in the press here (and in Britain and in the US) about America's 'gun culture' and 'love of guns'. As Jon noted, the Irish Times's Conor O'Clery made that very point in his report on the shooting in Minnesota.
However, I think focusing on guns is wrong. I know it's a cliche to say "guns don't kill people, people do", but there's a lot of sense in that. What society should be asking is, "Why these kids do what they do?". Why are they so disenchanted and disaffected that they carry out what are clearly self-destructive killings?
I think the problems that these kids have that lead them down this path of killing and self-destruction are mirrored in Europe by the lure of jihad among Muslim boys/young men. That the killers in the US are not from an easily identifiable social group makes labeling them more difficult (and more difficult for law enforcement to identify and track), but in both the US and Europe those attracted to killing and self-destruction seem to experience a great sense of alienation from the cultural mainstream.
We may not be able to do anything about it, but we should at least know what the motivation is. We should try to pinpoint the source of it. Focusing on the means of killing and not the motivation is pointless.