A preliminary 3.9 magnitude earthquake struck at 6:29 p.m. Monday near San Leandro, according to the United States Geological Survey.
The temblor, initially reported by the USGS as a magnitude 4.1, was felt across the Bay Area.
It was centered 2.1 miles north of San Lorenzo, 2.2 miles west-northwest of Castro Valley and 2.2 miles east-southeast of San Leandro, the USGS said.
Earthquakes of this magnitude are felt along communities within the Hayward Fault zone including Fremont, Union City, San Leandro, Hayward, Oakland, Berkeley and El Cerrito.
Monday's event was felt as far north as Santa Rosa, east into Solano County and south to the Santa Cruz area.
The last major earthquake on the Hayward Fault was a 6.8 earthquake in October 1868.
No other information was immediately available. Updates to come.