An 11-year-old was arrested Wednesday after police in Vancouver, Wash. say he brought a handgun, more than 400 rounds of ammunition, and several knives to his school.

Police told Q13Fox.com that the boy, a student at Frontier Middle School, was charged with one count of attempted murder and booked into the Clark County Juvenile Detention Center.

The boy said he heard voices in his head telling him to shoot another boy that he thought was bullying his friend, police said in a court document.

Police said he claimed in the presence of school officials that a "voice in his head" was telling him to kill another 11-year-old student for "calling his friend ... 'gay.'"

Commissioner Dayann Liebman ordered a mental competency hearing for the boy who remains in custody.

The boy's mother called the school and said her son had taken some kitchen knives. The school resource officer took the boy to the principal's officer where police said they found a .22-caliber handgun in his pants pocket and two loaded magazines in another pocket. More ammunition and the knives were found in the backpack, police spokeswoman Kim Kapp said.

Police said in an affidavit the boy told authorities he planned to shoot the student he felt was bullying his friend "in the arm and then shoot himself in the head."

The school, which has about 900 students, was placed in lockdown for approximately two hours while officers searched the campus following the boy's arrest. No injuries were reported.

The boy has been expelled, Evergreen Public Schools spokesman Kris Fay said.

"This kid has not been on the radar for this," he said. "From the safety standpoint, everything went well yesterday," Fay said.

The incident comes close on the heels of a series of violent incidents targeting school teachers this week. On Monday, a 12-year-old boy shot and killed a teacher and wounded two other students outside a middle school in Nevada before turning the gun on himself.

On Wednesday, a 14-year-old boy was arrested and charged with the murder of a math teacher at a Massachusetts high school.

Click for more from Q13Fox.com

The Associated press contributed to this report.