Updated 8:20 a.m.
A 4.0 earthquake shook the central Bay Area at 6:49 a.m. Monday.
The U.S. Geological Survey says the quake was centered in the Oakland Hills, just north of Piedmont, apparently on the Hayward Fault.
There were no reports of damage or injuries, though BART stopped service briefly -- its normal procedure after a temblor, to check that tracks are OK -- and reported a 10-minute systemwide delay. The California Highway Patrol's Golden Gate Division also reported no damage to bridges and highways. (And yes, the eastern span of the Bay Bridge is fine.) The quake was followed by a half-dozen aftershocks, magnitude 1.4 to 2.3, in the hour following the main quake.
The USGS "Did You Feel It?" page suggests the short, sharp quake was felt mostly in the East Bay and northern San Francisco Peninsula, with relatively few reports from the South Bay and North Bay.