Administrators secured all students in their classrooms at Valley Center Middle School while an ordnance-handling team searched the house just north of the campus, Sgt. Frank Gallardo said.
All students were safe at all times and were given lunch inside their classrooms, according to officials with Valley Center-Pauma Unified School District.
Shortly after 1 p.m., deputies gave the school an all-clear to lift the lockdown. Bomb squad personnel completed their search of the home about a half-hour, finding no explosive materials, the sergeant said.
The suspect's name was not immediately available.