After a snapped support cable struck three cars on the upper deck at around 5:45 p.m., the Bay Bridge was shut down in both directions this evening to check the structural integrity, according to ActionNewsSF.

SFGate reports:

CHP Officer Peter Van Eckhardt said what appeared to be a cable and a steel bracket fell from the eastern span's overhead steel support structure and onto the upper deck. The parts fell at about 5:30 p.m. Eckhardt said the passengers in one vehicle hit by the falling debris were shaken up but not injured.

Mercury News, however, says that one person has been injured.

Expect major delays. Check 511 for updates on traffic.

Update (7:45): Image of Bay Bridge overpass empty after tonight's closure went into effect. CHP is now diverting eastbound traffic onto Fourth Street. Also, Muni line 108 Treasure Island service has been suspended until further notice.

Update (8:08): The bridge will be closed for "at least 24 hours." Vehicles are backed up at the toll plaza. Nightmareish scene tonight, folks.