A magnitude 5.2 earthquake near Julian rattled much of Southern California just after 10 a.m. Monday, prompting brief evacuations in downtown San Diego and shaking cities as far away as Oxnard and Palm Springs.

The temblor, with an epicenter 3 miles south of Julian, caused especially hard shaking there and in Ramona, San Diego Country Estates, Pine Valley and Cuyamaca Rancho State Park, according to the U.S. Geological Survey.

By 11:30 a.m., it had produced four aftershocks in the 3.0 to 3.9 range. Sequences of this kind rarely lead to much larger quakes.

There were no immediate reports of widespread damage, but the California Highway Patrol received several reports of rock slides around the region.

Callers told dispatchers that boulders had fallen and were blocking some lanes on state Route 76 near East Grade Road near Lake Henshaw, and that there had been a rock slide on La Cresta Road near Flume Road in the Granite Hills area, just east of El Cajon.

The North County Transit District adjusted service in response to the quake, operating Sprinter trains on a reduced schedule and Coaster service on a speed restriction, with a bus bridge between Solana Beach and Sorrento Valley.

The temblor started 8.3 miles deep, immediately south of the Elsinore fault zone — one of the busiest seismic zones in California, according to the USGS.

The 190-mile long strike-slip fault extends from near the U.S.-Mexico border through San Diego County to the northern end of the Santa Ana mountains near Los Angeles, and it is capable of producing a quake as powerful as 7.5.

Many people who subscribe to ShakeAlert, a USGS early warning system, received notices of the quake on their phones and watches Monday a second or two before they felt it.

In Santa Ysabel, the shaking tossed around merchandise at the Barn Vintage Marketplace.

Owner Brandi Smothers was in the kitchen at her nearby home when her antique pottery “came flying off the shelves.” She headed to her shop and found old antique mirrors “down off the shelves and broken.”

The second floor was a little harder hit. “Anything that could fall is on the ground,” she said — but still, she added, “I’m thinking we probably got away OK.”

At the nearby Julian Pie Shop, office manager Robin Young was talking with a customer when the earthquake hit.

“It was pretty powerful. It was intense,” Young said. But “it didn’t last long enough to get a chance to react. Everyone froze.”