After nearly half of the Fir Grove Elementary student body and staff became ill with stomach flu-like symptoms Thursday, the Roseburg School District closed the school at noon and sent everyone home. The school will remain closed until Tuesday while workers sterilize the building. The school was already scheduled to be closed Monday for Veterans Day. A Douglas County health official said today it’s unknown how the fast-moving illness originated, though Roseburg School District Superintendent Larry Parsons said the sickness doesn’t appear to be related to food served at the school, which has about 300 students in kindergarten through fifth …