A school project provoked a Gilbert police department response and a lockdown at Williams Field High School on Friday.
Police were alerted after a parent observed what he or she thought was a student walking across campus with a rifle.
The school was in lockdown for 30 minutes as police searched the area, police said. The student returned to school after seeing the police response and explained that he carried the replica home after school.
"The police department appreciates the diligence of community members for calling in this suspicious activity," said Sgt. Jesse Sanger, spokesman for the department. "As always we encourage citizens to report any type of suspicious activity, regardless of how small the situation may seem."
The school will conduct its own administrative investigation, Sanger said.
Williams Field High School is in the Higley Unified School District.