KENT, Wash. — A high school south of Seattle has added extra security Monday after anti-Muslim graffiti and threats were found on campus last week.

Chris Loftis of the Kent School District tells KOMO-TV the graffiti and written threats were found last week in the girl’s restroom at Kent-Meridian High School.

School officials notified parents in a letter Friday that a staff member found graffiti threatening students of Muslim heritage. The threat mentions Monday so additional security personnel are on duty.

Kent police are investigating.