California has been hit its strongest earthquake in 20 years.

The 7.1 magnitude quake struck on Friday night and centred on the town of Ridgecrest in the Mojave Desert, where a 6.4 magnitude quake struck on Thursday.

Offices in downtown Los Angeles shook for around 30 seconds and the rumble was also felt in the Hollywood Hills, Las Vegas and parts of Mexico.

No deaths have been reported.

Officials said there have been "multiple injuries and multiple fires" but that it appeared that no buildings had collapsed.

Food that fell from the shelves litters the floor of an aisle at a Walmart following an earthquake in Yucca Yalley, California, 05-07-2019. Image: Chad Mayes via AP

Mark Ghillarducci, head of the California Office of Emergency Services said there are “significant reports of structure fires, mostly as a result of gas leaks or gas line breaks.”

Lucy Jones, a seismologist with the California Institute of Technology, said Thursday’s quake was a "foreshock" in the run-up to the larger shake on Friday night.

Celebrities reacted to the tremor on social media, 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

Hundreds of aftershocks have jolted the area since Thursday's initial earthquake and experts say they could continue for three years.