ORLANDO, Fla. – Lake Highland Preparatory School welcomed students back for the first day of the fall semester Thursday and was temporarily placed on lockdown while authorities searched for a suspect near the campus, according to school staff.Orlando police responded to a potential threat at a nearby chiropractor’s office prompting the lockdown, according to the police department.Police said a man went to the office at 206 East Colonial Drive at about 1:30 p.m.