SEATTLE -- A 10-year-old Washington state boy was sentenced on Wednesday to up to 5 1/2 years in a juvenile detention facility for his role in a foiled plot to rape and kill a girl at his school and harm other children.

The boy was charged with conspiracy to commit first-degree murder, juvenile firearm possession and witness tampering in connection with a plot in February at an elementary school in Colville, in the state's northeast.

Prosecutors said he pleaded guilty last month to all charges.

Stevens County Superior Court Judge Allen Nielson sentenced the fifth-grader to a minimum of just over three years in juvenile detention and a maximum of nearly 5 1/2 years, Stevens County prosecutor Tim Rasmussen said.

An 11-year-old boy accused of joining in the plot is charged with conspiracy to commit first-degree murder, possession of a dangerous weapon in the form of a knife at school and tampering with a witness, Rasmussen added.

The 11-year-old suspect faces a court hearing later this month.

The 10-year-old boy will serve his sentence at the Echo Glen children's juvenile center in Snoqualmie, Wash., 45 miles east of Seattle. As of Thursday he had already spent nearly 100 days in a local juvenile detention facility, Rasmussen said.

The boy told investigators he and his friend had planned to kill a former fifth-grade girlfriend because she was "rude" and "always made fun" of him and friends, according to court documents.

They plotted to entice the girl away from their elementary school, the court papers stated.

The 10-year-old had taken a Remington Model 1911 pistol that originally belonged to his grandfather from his older brother's room, according to court records.

The boys had also packed ammunition and a knife, but they were stopped on Feb. 7 shortly after they boarded a school bus, Rasmussen said.

A fourth-grade student spotted the knife and reported it to a teacher's aide, Rasmussen said. The names of six other targeted classmates were on a list the boys had, Rasmussen said.

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SEATTLE -- Two fifth-grade boys are in custody in Washington state after they brought a knife and gun to school with the goal of killing a schoolmate in a foiled murder plot that shocked their rural town because of their youth, prosecutors said on Friday.

The boys, accused of conspiracy to commit first-degree murder despite their tender ages of 10 and 11, also planned to harm other students by luring them away one at a time, said Tim Rasmussen, a Stevens County prosecuting attorney.

The boys are due in court next week, where a judge will determine if they had the mental capacity to carry out the attack and if they can be prosecuted in juvenile court, which in Washington is typically reserved for older defendants between ages 12 and 18.

Prosecutors said the boys had boarded a school bus on their way to an elementary school in Colville, a city of 4,600 residents in the far northeast part of the state, with the 11-year-old in possession of a knife and the 10-year-old with a functional Remington Model 1911 semi-automatic handgun.

But a fourth-grade student riding the bus saw the knife and reported it to a teacher's aide, prosecutors said. School officials found the weapons before anyone was hurt, and the two boys were arrested. They are in a juvenile detention facility.

The boys sought to lure the girl away from school, where the older boy planned to stab her, prosecutors said.

"I was going to kill her with the knife and (the younger boy) was supposed to use the gun to keep anyone from trying to stop me or mess up our plan," the older boy told police, according to the declaration of probable cause filed in court.

They intended to kill the girl because "she's rude and always made fun of me and my friends," the younger boy told investigators, according to the documents.

Attorneys for the boys declined to comment.

One of the boys had taken the gun, which originally belonged to his grandfather, from an older brother's room, according to a declaration of probable cause.

The boys also bribed another student with $80 to dissuade him from revealing what he knew about the plot, Rasmussen said.

In addition to the murder conspiracy, the 10-year-old boy faces charges of being in possession of a firearm and tampering with a witness.

The 11-year-old faces charges of murder conspiracy, juvenile firearm possession conspiracy and tampering with a witness.

If they are convicted of all the charges they could be sentenced to over three years in a juvenile treatment facility.

Copyright 2013 Thomson Reuters. Click for restrictions.