Dumbarton Bridge reopened after police activity

MENLO PARK, Calif. (KGO) -- Police activity closed all lanes of the Dumbarton Bridge early Monday morning.

Lanes were closed from 3:30 a.m. to 4:30 a.m. Authorities did not say what caused the police activity.

No injuries have been reported and traffic has been back to normal.

Stay with ABC7 News for the latest details on this developing story.