Gus Van Zant’s “Elephant” is a movie without answers, a fact that will deeply frustrate and anger viewers who crave some sort of tidy, easy-to-disassemble explanation for one of the most troubling, inexplicable days of violence we’ll ever know.

Modeled after the Columbine shooting spree, “Elephant” leaves the social forensics to someone else. There is no flash, no insight, no probing examination of adolescent nihilism — the movie is strictly observational, and for that reason, enormously powerful and brave, capturing the simple, chilling truth of the tragedy in a way that forbids us to explain it, forget it and move on.

Van Zant (“Good Will Hunting”), using teenaged non-actors and improvised dialogue, pokes his camera in and around an Oregon high school on an average school day. The conversations are mundane, the encounters ordinary — in one snippet, a trio of bulimic mall girls negotiate hangout time with a seriousness and self-absorption that would befit Middle Eastern diplomats — yet all are afforded a certain relevance by the horrid collision that we know lies in wait.

At first, it's not immediately apparent who the shooters will be, but gradually two of the students reveal symptoms that the country has come to associate with the so-called Trenchcoat Mafia. Antagonized by jocks in his science class, alienated Alex (Alex Frost) spends his afternoons with Eric (Eric Deulen), playing carnage-ridden video games, half-interestedly watching a Hitler documentary and ordering assault weapons over the Internet. Alex is not a neglected, uncultivated child — at one point, he pounds out Beethoven’s “Fur Elise” on the piano (an homage to “A Clockwork Orange,” perhaps) — although his parents, naturally, are virtual non-entities.

Van Sant doesn't exploit Alex and Eric for dramatic value; the lack of a musical soundtrack, backstory and conventional narrative techniques (much of the film consists of long, unbroken tracking shots) make the whole thing seem creepily, insidiously natural. Van Sant could be suggesting that the boys have no real grasp of reality themselves, that something, somewhere made them numb, much like the movie seems to be.

But just because “Elephant” — which picked up the Golden Palm at the 2003 Cannes Film Festival, along with a directing award for Van Sant — doesn’t provide insight, don’t assume it lacks emotional contour. Among the characters, I was touched by one kid, Eli (Elias McConnell), who spends much of the movie taking snapshots of his fellow students for a photography project. There’s nothing particularly profound about what he says or does, but you can tell he likes being around his classmates, and more than that likes the variety of them. And there you have it: one student who shoots people because he feels for them, two others who shoot people because they feel nothing at all.