Edison Elementary School in Tacoma has been evacuated due to fumes from a gas-powered leaf blower being used on the school's roof.
Tacoma Fire treated 47 staff and students for headaches, nausea and dizziness. Eighteen patients were transported by ambulance and 27 patients were taken by school bus to local hospitals for treatment.
Haz-mat vented the building and check air before they cleared it for students to re-enter.
Dan Vopel, spokesman for Tacoma Schools said the incident started around 9:30 a.m.
A parent check-in station is open on campus for parents of students. Families were notified of the incident by a recorded message.