A middle school student in Pinole caused a campus lockdown on Monday after bringing a pellet gun to the school, police said.

Pinole police spokesman Lt. Matt Avery in a statement said police were investigating the incident at Pinole Middle School, located at 1575 Mann Dr. Avery said police will refer the case to the Contra Costa County District Attorney’s Office and to its Juvenile Probation department.

School officials also are investigating. West Contra County Unified School District spokesman Ryan Phillips said school policy defines any replica gun as a weapon.

The school is expected to discipline the student.

The pellet gun never was fired, and the incident did not lead to any injuries, Avery said.

School officials contacted police just before 9 a.m. to report that a student on the campus might have a gun.

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Avery said that as officers responded, school administration detained the student in the school office. They also placed the campus on lockdown.

When school officials searched the backpack, they found the pellet gun, Avery said.

School officials lifted the lockdown by 12:30 p.m.

Pinole police asked anyone with information to call them at 510-724-8950.