The U.S. Geological Survey says the magnitude-5.7 quake was centered five miles southeast of Ocotillo near the U.S.-Mexico border. It struck Monday at about 9:30 PDT, and was initially reported as a magnitude-5.9 temblor.
Several aftershocks, measuring between 3.2 and 3.9, followed.
It was felt as a gentle rolling motion in Los Angeles, Long Beach and Orange County. San Diego's Petco Park swayed, and the public address announced asked that everyone remain calm. The crowd cheered.
David Eckstein of the Padres had just grounded out in the bottom of the inning when the stadium began shaking. The next batter, Chase Headley, stayed out of the batter's box for a few seconds, then stepped in.
San Diego Sheriff's dispatch supervisor Becky Strahm said some of her colleagues reported things falling off their shelves, but there were no immediate reports of significant damage or injury.
The quake follows a series of temblors that struck Southern California over the weekend, including a pair of moderate earthquakes that rattled a desert area east of San Diego. Residents in downtown San Diego could feel the ground rumbling during at least one of the Saturday quakes.
There are no immediate reports of damage or injuries from Monday night's earthquake.