A fire that ripped through a classroom at Sacramento’s Grant High School was deemed suspicious, fire investigators said Monday morning.

Firefighters responded about 10:22 p.m. Sunday to reports of a fire at the school on Grand Avenue. When crews arrived, they spotted flames in a building behind the school’s auditorium.

About 70 to 80 firefighters helped extinguish the flames. One classroom was completely destroyed, the fire department tweeted out.

Sacramento fire officials said the blaze could possibly be arson, but have not said if there are any persons of interest.