A 14-year-old Timber Creek High student has been arrested after a fire was started in the school's bathroom Saturday morning, investigators said.Authorities said there was a loud boom inside one of the restrooms at Timber Creek High School, followed by smoke and fluid coming from it.Teachers and students were forced to evacuate one of the campus buildings where a debate tournament had just began.The Orange County Sheriff's Office said surveillance video shows someone running into the first-floor bathroom and exiting moments after the explosion.In a secondary sweep of the school, investigators said they found another restroom had been set on fire.Authorities have not revealed what caused the sound or the smoke, but are calling this a case of arson.There were no reported injuries. The student is charged with arson in the first, which is a felony and two additional misdemeanor offenses, according to authorities. School activities will resume on Sunday.