A 12-year-old boy is accused of plotting to shoot students and others at his Dallas charter school after he was found clutching a detailed diagram outlining the planned attack, a police commander said.
    The plan was uncovered when the boy showed the handwritten diagram to another student who then alerted administrators at Trinity Basin Preparatory, according to Assistant Police Chief Randall Blankenbaker. The boy was still clutching the diagram when he was taken to an office at the public charter school.
    He was arrested and charged Thursday with a felony count of exhibition of a firearm and was being held at a juvenile detention center. The boy had no weapon with him at school and it's not clear if he had access to firearms elsewhere. Authorities say he was charged simply because he threatened to use a firearm to harm others.
    "A reasonable person would see this diagram and they would believe that he intended to carry out his threats based on what's on the diagram," Blankenbaker said at a news conference Thursday evening.
    Blankenbaker said the boy had tried several time to recruit the second student to help him carry out the attack, but his threats were dismissed as a joke until he showed that other boy the diagram.
    Blankenbaker described the second student as "courageous" for alerting school administrators.
    The incident was the second in about a week involving a threatened attack on a Dallas-area school. A 15-year-old boy was arrested after police say he threatened to open fire at a high school in Forney, east of Dallas, The Dallas Morning News reported.