San Francisco's Bay Bridge was shut down Tuesday and was expected to stay closed indefinitely after a piece of the bridge fell onto the roadway, the California Highway Patrol said.

The piece of steel and cable that fell from overhead initially caused a minor car accident, which backed up traffic for miles, said CHP Officer Peter Van Eckhardt. No one was injured in the accident.

That section of the bridge, which had recently been repaired, will be reinspected before the span reopens, officials said.

All eastbound and westbound lanes were shut down at 8 p.m. PT Tuesday, Van Eckhardt said.

Public transit agencies throughout the Bay Area were told to brace for an expected increase in ridership Wednesday, the officer added.

About 280,000 vehicles cross the Bay Bridge every day, according to the California Department of Transportation.

A 50-foot section of the bridge collapsed in 1989 during the Loma Prieta earthquake, killing one person, prompting efforts to make it quake-tolerant.