A 13-year-old pupil at East Middle School in Westminster was arrested after he took a knife to school last week, police said.
Westminster police said they arrested the boy Friday morning after other pupils told school officials that he had shown them a knife while they were riding the bus to the school.
Authorities found a knife with a 2 1/2 -inch blade in the boy's pants pocket when he was called to the principal's office, police said.
Capt. Randy Barnes said police were not aware that the boy made any threats with the knife.
The boy has been suspended from school and released into his parents' custody, police said.
Under Carroll school regulations, students who take knives with blades up to 2 1/2 inches long onto school grounds may be suspended for up to five days.