A strong earthquake struck early Friday morning far off the coast of California, the U.S. Geological Survey reported.

The magnitude 6.3 quake struck at a depth of 6 miles, about 163 miles southwest of the nearest city, Avalon, on California’s Santa Catalina Island, at 2:36 a.m. PT (5:36 a.m. ET), the USGS said.

Earlier reports indicated that two earthquakes struck 17 seconds apart, but the USGS later confirmed that only one quake occurred.

No tsunami warning was issued.

Reports of shaking came in from San Diego up to Huntington Beach, but no major reports of damage are expected, according to NBC News affiliates in the area.

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