The incident was reported at 12:08 p.m. on Thursday, during the last period of the shortened "minimum" last day of school before winter break.
"There was a student running around, scaring students," Chino Valley Unified spokeswoman Julie Gobin said Friday.
Student Kritesh Bhakta was allegedly racing around campus, wearing an Albert Einstein mask, according to San Bernardino County Sheriff's Department spokeswoman Cindy Bachman.
Seeing the mask-wearing student, Ayala High students ran into the front office in a panic, and officials triggered the lock down, which lasted about 10 minutes.
"They didn't recognize the student and he was pulling a prank," Gobin said.
Bhakta reportedly ran off campus, where he was arrested by the campus security officer, a San Bernardino County Sheriff's Department deputy. He was booked at West Valley Detention Center for causing a disturbance on school grounds, and released Thursday night with a citation.
Police had investigated a rumor of a possible threat against the school earlier in the week.
Staff writer Doug Saunders contributed to this report.