Federal law enforcement officials say a 16-year-old student in Minnesota appeared to be acting alone when he shot dead nine people and then killed himself during Monday's violent rampage on a remote Indian reservation.

FBI officials say Jeff Weise first killed his grandfather and his grandfather's companion at home. Authorities say the grandfather was a police officer on the Red Lake Indian Reservation, and the boy took his gun and bullet-proof vest before driving his police cruiser to school.

The FBI says Jeff Weise killed an unarmed security officer at the school entrance. He then shot dead a teacher and several students before roaming the hallways, firing randomly. The boy killed himself after exchanging gunfire with local police. Five students remain hospitalized for gunshot wounds.

President Bush called the shootings a "terrible tragedy" and said his thoughts and prayers were with the victims' families.

The rampage was the deadliest school shooting since the 1999 Columbine High School massacre in Colorado left 14 students dead.

Some information for this report provided by AP.