Authorities say a boy who fired on classmates and wounded one at a rural California high school had planned the attack and targeted students he felt had bullied him for more than a year.

Kern County sheriff Donny Youngblood said at a news conference Thursday night that the 16-year-old used a shotgun that belonged to his brother and went to bed Wednesday night with a plan to shoot two fellow students.

Youngblood says surveillance video shows the boy trying to conceal the gun as he nervously enters Taft Union High School through a side entrance after school had started Thursday morning.

The boy entered his classroom, shot and critically injured one student, then fired on others before a teacher and another staff member talked him into surrendering.