FREDERICK, Colo.—A Colorado mom with a nose for trouble marched her son into the principal’s office and said he was planning to set off a stink bomb at the school.

Frederick High School was briefly evacuated on Thursday after the woman reported the alleged plot. There were no reports of any would-be bombs going off.

Police Chief Gary Barber says officers found a bag the boy had left near the school containing such ingredients as baking soda, flour, sugar and salt. Barber says the concoction would have to be set on fire to produce fumes, and it wasn’t clear if they’d be noxious.

It’s not certain what kind of punishment the boy might face. No names were released.

Frederick is a town of 8,200 about 25 miles north of Denver.

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Information from: Daily Times-Call, http://timescall.com/