FREMONT, Calif. - Fremont police were seen going door to door in a residential neighborhood on Friday.
It's unclear what they were investigating.
The department tweeted that officers were active in the neighborhood around Mowry Avenue and Farwell Drive.
Nearby Mattos and Azevada elementary schools were placed on lockdown for about an hour on Friday afternoon, but the schools were allowed to resume normal activities at 2:17 p.m., the Fremont Unified School District said.
Police said that they had completed their work in the neighborhood around 3:40 p.m. and that roads were reopened.