A Sig-alert was issued early Friday when a truck rammed into an overpass on westbound Interstate 80 in San Pablo.
The crash sheared off the truck's container around 5 a.m., scattering debris just past San Pablo Dam Road. Lanes 3 and 4 are blocked, causing traffic to back up for miles.
The California Highway Patrol has urged drivers to use alternate routes, noting that they don't have an estimated time of reopening the closed lanes.
Check back for updates.