The SBI is assisting Kinston firefighters as they try to determine what started an early morning fire at Kinston High School.
Classes for students were cancelled.
The fire is believed to have begun in the back of the cafeteria, in a dishwashing room around 1:00 a.m.
Officials say they do not suspect foul play, and that the SBI is there because it happened at a public school.
"There's really nothing to indicate that this was anything other than a naturally occurring fire, if you could call it that," said school systems spokesman Patrick Holmes. "There's no indication that there's a suspicious nature to it, sign of forced entry or nothing."
Once investigators finish their work, contracted clean-up crews will be brought it to start with the clean-up. Administrators say they will work around the clock to make sure the high school can reopen for the 700 students on Monday.