A police investigation near the campus of Fountain Valley High School prompted the school to be placed on a lockdown Tuesday morning.

Students and teachers were asked to remain in their second-period classrooms before 10 a.m. Tuesday in response to an incident on Talbert Avenue. That changed to a shelter-in-place alert at 11 a.m. which barred students from leaving. All security measures were lifted at 12:45 p.m., said Principal Morgan Smith.

The lockdowns were ordered by the schools after SWAT officers served a search warrant in the 9000 block Talbert Avenue, Westminster police Cmdr. Cameron Knauerhaze.

Westminster police were working an operation in the area, but would not provide further details about the nature of the investigation.

Smith said the police activity was related to an investigation at a home on Talbert Avenue.