Residents across Southern California received an unexpected jolt this afternoon when a 3.5-magnitude earthquake, according to the U.S. Geological Survey (USGS), struck near Ontario. Initially reported as a 3.1-magnitude shaker, the USGS later revised the strength of the quake, which hit at approximately 12:56 p.m., with the epicenter located a mere 1.24 miles southeast of Ontario, according to CBS News Los Angeles.