A high school was put on lockdown for about two hours Monday after a student reported seeing a teenage boy with a gun.

Paradise Valley School District spokeswoman Audrey St. Clair confirmed the lockdown at Horizon High School had been lifted later Monday morning but declined to elaborate.

A call to Phoenix police was not immediately returned.

Phoenix police Detective Stacie Derge had said earlier that police were searching the campus for the teenager after the 8:40 a.m. report.

She said authorities didn't believe the teenager was a student at Horizon.

The school posted a notice on its Web site saying all students and staff were safe, and that the lockdown was lifted at 11 a.m.

According to the school Web site, Horizon has about 2,300 students in grades nine through 12.