A 7.1-magnitude earthquake has hit California less than two days after another strong tremor, rattling parts of LA and causing fire and building damage near its rural epicentre.
The quake hit at 8.19pm local time 11 miles from Ridgecrest in the Mojave Desert, the site of Thursday's 6.4-magnitude quake.
Offices in downtown Los Angeles shook for around 30 seconds, and the quake was also felt in the Hollywood Hills, Las Vegas and parts of Mexico.
The earthquake is the strongest to hit the region in 20 years, with experts giving it an early rating of 6.9 to 7.1 on the Richter scale.
There are "significant reports of structure fires, mostly as a result of gas leaks or gas line breaks" in Ridgecrest, said Mark Ghillarducci, head of the California Office of Emergency Services.
He said the full extent of the damage would not be revealed until daybreak on Saturday.
There have been minor injuries but no reports so far of anyone seriously hurt or killed.
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Lucy Jones, a seismologist with the California Institute of Technology, said the quake was part of the sequence that produced the earlier quake, saying Thursday's quake was a "foreshock".
She said there is about a 1-in-10 chance another 7.0-magnitude quake could hit in the next week.
Some California residents posted videos on social media of their swimming pools sloshing around as the tremors struck.
Disneyland in Orange County and Six Flags Magic Mountain in Santa Clarita closed their rides, and a NBA Summer League game in Las Vegas was stopped.
Celebrities in the area also reacted to the quake, with actor Stephen Fry tweeting: "Whoa! Was that aftershock just now or a whole new quake? 8:20pm #Earthquake."
"Certainly felt it here in the Hollywood Hills," added Fry.
Whoa! Was that aftershock just now or a whole new quake? 8:20pm #Earthquake
— Stephen Fry (@stephenfry) July 6, 2019