Evergreen Public Schools says York Elementary was briefly placed on lockdown during the Tuesday morning dispute.
Sgt. Fred Neiman says school staff called 911 to report that an irate parent had forced her way into the principal's office and was threatening the principal.
Neiman said 25-year-old Ciera Davis was arrested for investigation of fourth-degree assault and booked into jail.
The Columbian reports it was the district's second lockdown in a week. On Oct. 23, a student at Frontier Middle School was arrested after he was found with a .22 caliber handgun and 400 rounds of ammunition. The student remains in custody.