Three trailer homes burned down in a fire on the South Side on Thursday night in Billings, and the Billings Fire Department planned to continue monitoring the site overnight. A call came in at 6:06 p.m. that a trailer home at 37 Washington Street was on fire and that the fire had possibly extended to a second structure, Assistant Fire Chief William Rash said. Crews arrived and determined that at least two structures were burning, and additional structures were at exposure risk from fire.