A magnitude-5.4 earthquake could be felt across Southern California late Wednesday afternoon.
The quake struck at 4:53 p.m. The epicenter (map) was located about 13 miles north-northwest of Borrego Springs and 25 miles southwest of Indio.
A preliminary reading listed the quake at magnitude 5.9. It was later downgraded to 5.4, according to the U.S. Geological Survey.
No major damage or injuries have been reported so far, according to fire departments in Borrego Springs, Orange County, Los Angeles city and county.
About six people were struck in the service and public elevators for about an hour at the Agua Caliente Casino Resort Spa in Rancho Mirage, said casino spokeswoman Therese Everett-Kerley.
A rockslide was reported near the Palm Springs Aerial Tramway, but officers determined there was no damage as a result of the slide.
Officials at Los Angeles International Airport said the airport was operating normally, with no reported flight disruptions. The Los Angeles Department of Water and Power reported that it had no impacts from the quake, and no known disruptions in water and power service. Southern California Edison also reported no outages.
Metrolink train service was also unaffected.
The shaker was followed by a series of aftershocks in the Borrego Springs area, most measuring around magnitude-3.0.
"@NBCLA: Felt that all the way up in Valencia. Came on very intense and very quickly, rolling motion, lasted about 20 seconds," tweeted Nicole Elliott.
"@NBCLA i'm in la crescenta and i felt it. smooth rumbling rolling by. felt like a kiddie ride at disney land with some motion," tweeted Michael Johnson.
"@NBCLA i was playing mafia wars when i felt the shaking in our apartment in Alhambra," tweeted Elgin Aller.
"@NBCLA I felt the earthquake ... it had my daughter & I rollin rollin rollin .. we felt like we were out on a boat in the ocean," tweeted La Shanda Franklin.
"@nbcla Up here at 6200ft in Mt Baldy, quakes always feel like one big jolt--like someone bumped into the top of the mountain! This one, too," tweeted S Kay Murphy.
"@NBCLA We live in Temecula. We were at a dance class, watching a Hip Hop show. We thought the place was thumpin and the people were jumpin," tweeted Lisa Masters.
Quake Struck on San Jacinto Fault Zone
USGS seismologist Kate Hutton told reporters at Caltech in Pasadena that the quake likely occurred in the San Jacinto fault zone, and it was followed by about two dozen small aftershocks, the largest a magnitude-3.6.
The fault zone is located along the San Jacinto Mountains. It runs from near the Salton Sea area northwest toward San Bernardino.
It was the strongest quake to hit the area since the Easter Sunday earthquake.
Hutton said residents should take Wednesday's quake as a warning to be prepared for temblors.
"The best way for people to look at this earthquake is that it's a drill," she said. "... If this one had been the big one, what would I have done? Would I have been prepared? Would I have had my supplies, my plan and all that? ... So review everything, check your kit, because we can't predict earthquakes, we don't know when they're going to happen, so we have to be prepared all the time."