Ms Gabrielle Giffords, a Democratic representative in Arizona, was shot into her head. Several others have been killed. She's in critical condition but after the surgery, doctors are optimistic.
See all five videos he has posted
The shooter was almost certainly 22-year-old Mr Jared Lee Loughner and the video above tells us something about him.
Well, he had a good taste for music and he could create semi-professional YouTube videos. More importantly, he's been clearly a nutcase.
For example, the video above argues that the years of the Common Era couldn't have begun because they could only come after the years before the Christ. But the latter had to start, too. But because the number minus infinity doesn't belong among the real numbers, it couldn't have started.
(Just to be sure, the mistake is the assumption that subsets of integers have to have a minimum: the set of integers itself doesn't include any minimum.)
The killer's MySpace page has been taken down.
He offered similar "arguments" why you can establish a third currency and a third language, among other things. Final slides are directed against the federal U.S. government and against God. But I would obviously not recognize his ideas as some values I find important.
This event is a tragedy. It is more likely that the shooter is a lunatic - a self-described sleepwalker and terrorist - who could have emerged at any time and his act occurred today by a coincidence - rather than as a reaction to some recent events.
A sleepwalking episode may look like this - unless the actors are bad. ;-)