Search for motive in Minnesota school shootings

Authorities were today trying to determine what caused a teenager to gun down his grandfather, put on the man’s police-issue belt and bullet-proof vest, and drive his marked squad car to a high school, where he began shooting his classmates at will.

Jeff Weise, 16, killed nine people and wounded seven on Monday before trading gunfire with a police officer and apparently shooting himself. His motive still wasn’t clear yesterday, but the FBI said the shootings appeared to have been planned in advance.