UPDATE: The Bakersfield Police Department said it has learned the report came from a student who thought he saw another student with a gun.
The department said the student alleged to have had a gun left the school prior to officers' arrival and that there was no evidence of any firearms-related incidents, fights or threats.
The department said the students knew each other and have had previous conflicts.
The lockdown has been lifted.
West High School is on lockdown following a report of a gun on campus. The Bakersfield Police Department is on scene searching the campus but no gun has yet been found.
West High Athletic Director Scott Davisson said a varsity baseball game was going on at the time of the lockdown. Players, coaches, fans and umpires were evacuated from the fields by police.
Police said at around 4 p.m., officers got the report and were sent to the school, located at 1200 New Stine Road. School was not in session at the time of the report.
BPD said it has found no evidence yet that someone was seen with a gun on campus.