Just one day after Methuen High School was evacuated and closed because of an e-mailed bomb threat, police arrested a 15-year-old student Thursday for allegedly making a new threat.
The arrest of the student, who lives in Methuen but whose identity was not released, is not connected to Wednesday's threat and evacuation, police believe.
"Yesterday's incident remains an open and ongoing investigation," police said in a statement on Thursday.
According to police, the male student wrote a nonspecific threatening message on a piece of paper and left it in a bathroom Thursday morning. A staff member later found the note.
After being questioned by school officials, the student was arrested and charged with making a bomb threat, police said. The reason the student made the alleged threat is unknown. He will be arraigned in juvenile court.
J.D. Capelouto can be reached at jd.capelouto@globe.com. Follow him on Twitter @jdcapelouto.