ALAMEDA -- The lockdown at Alameda High School will be lifted by about 4:30 p.m., police said.

Police put the campus at 2201 Encinal Avenue on lockdown Monday afternoon after the principal told police she received a call from someone claiming he was in a restroom and armed with a knife.

Officers searched the campus but did not locate anyone suspicious, Alameda police Lt. Ted Horlbeck said.

No students have been hurt, Horlbeck said.

The caller sounded like a male, the principal told police, who are investigating the incident.

This article will be updated as more information becomes available.