Milton High School went into “stay in place” status for nearly two hours beginning at 1 p.m. Tuesday after a student found a metal object thought to be a bullet casing, said School Superintendent Mary C. Gormley. Initially Milton police and school administrators believed that the the object may have been a remnant of a nail gun used by a company working on the building. All students and teachers were instructed to remain in their classrooms, Gormley said in e-mail to parents. Police brought in six specially trained dogs that can detect ammunition, but no items of concern were found, Gormley said.