A reported 7.1 magnitude earthquake has struck Southern California just a day after another powerful quake hit the region.

Live footage of the moment the earthquake struck was captured live on ESPN as the NBA's Summer League showcase was going on during day one.

Fans had rocked up to catch a glimpse of number one draft pick Zion Williamson make his professional NBA debut but they were quickly exiting the building after a tremor rocked the building.

The game, which was played at the Thomas & Mack centre in Las Vegas, was brought to a standstill with more than 7 minutes to play in the final quarter as the overhead speakers and scoreboard began to sway.

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The U.S. Geological Survey says the 7.1 magnitude quake hit at 8:19 p.m. Friday and was centered 11 miles from Ridgecrest, a small desert town in Kern County. The quake was felt downtown as a rolling motion that seemed to last at least a half-minute, according to AP. It was felt as far away as Las Vegas, and the USGS says it also was felt in Mexico.

If the preliminary magnitude is correct, it would be the largest Southern California quake in 20 years.

Officials in San Bernardino County reported homes shifting, foundation cracking and retaining walls coming down. One person suffered minor injuries and was being treated by firefighters, they said.

Lucy Jones, a seismologist with the California Institute of Technology's seismology lab, tweeted that the quake was part of the sequence that produced the earlier quake.

The Los Angeles Times reports over 2,000 residents in Ridgecrest and surrounding areas are without power.