The boy was carrying out a deliberate plan when he shot five students at his
California high school, then turned the gun on himself, a local sheriff said on Friday, but authorities said they had no clues about what sparked the bloodshed.
Two of the other five students who were shot in the Thursday morning attack at the school in Santa Clarita died of their wounds.
"We did not find any manifesto, any diary that spelled it out,"
Los Angeles County Sheriff Alex Villanueva said at a briefing.