BOULDER, Colo. (AP) -- A high school in Boulder County is closed Friday as authorities investigate a threat to blow up the school and a threatening note with about 30 students' names.

A threat that Niwot High School was "going to blow on the 11th" was scrawled in a bathroom last Monday and made public Tuesday. The Longmont Times-Call reports the principal told parents Thursday that sheriff's officials recommended closing the school at the end of the day after students found the note.

Meanwhile in Colorado Springs, police notified school security officers throughout the city Thursday of a report of an alleged threat someone made referring to the school shooting in Newtown, Conn. Police said no specific Colorado Springs school was mentioned, and they didn't immediately have enough information to substantiate the threat.