The fire was reported about 5:15 a.m. on Tuesday morning at Franklin Middle School at 501 Starr Avenue.
This is the second crime at the school since classes resumed two weeks ago, and it is impacting hundreds of students and Vallejo Unified School District is going to have to shell extra money for repairs.
Benjamin Franklin Middle School had to scramble on Tuesday morning. About 260 sixth graders and their teachers were without a classroom due to a fire.
"It's early in the investigation, but it looks like this was deliberately set," said Jason Hodge from Vallejo Unified School District.
Vallejo Unified School District said arson on campus overnight damaged two portable classrooms. Investigators found that an accelerant was used. The damage and smoke smell was so bad, that the school moved students out of a section of the campus.
A group of sixth graders relocated to the cafeteria.
"We were going to work on out text books today and then I say okay what are we going to do instead since I don't have a board or anything right now. They are working on some worksheets," said sixth grade teacher Christal Watts.
For the students it's was also tough since there was a lot of confusion over what happened and where to go.
"We saw some kids going to different classes confused and asking teachers where to go," said sixth grade student Delshon Dixon.
This fire marks the second incident of vandalism in just two weeks at Franklin Middle School. Last weekend, the district said vandals took copper wire that connected power to the auditorium.
Vallejo Unified School District said they will install surveillance cameras at every school across the district.
"The video surveillance is going to cost some money, but in the long run we believe that we are going to save some money by getting a handle on all of the vandalism," said Hodge.
The damage estimate is still unknown, and the district said it could take a few more days for the sixth graders to get back to their classrooms.