USGS(LOS ANGELES) — A powerful earthquake with a preliminary 6.4 magnitude rocked Southern California on Thursday morning, officials said, as they warned that strong aftershocks are expected.

It was the strongest earthquake in Southern California since 1999, seismologist Dr. Lucy Jones said at a news conference.

Aftershocks will likely exceed a magnitude 5, Jones said.

“We will continue to have a lot of aftershocks,” Jones said. “I think the chance of having a magnitude 5… it’s probably greater than 50-50.”

The epicenter of the Fourth of July quake was in a remote area near Searles Valley in the Mojave Desert, which is about 150 miles northeast of Los Angeles.

Structure fires were reported in the nearby city of Ridgecrest, according to Kern County fire officials.

In San Bernardino County, the quake broke water mains, downed power lines, cracked buildings and caused rock slides on roads, officials said. No injuries or fires were reported in San Bernardino County, officials added.

The Los Angeles Police Department said it has not received any reports of damage or calls for service.

“This was a strong one, and a good reminder to be prepared,” the LAPD tweeted.

A tweet from the Los Angeles International Airport said no runways were damaged and the airport was operating as normal.

A tsunami is not expected, according to the National Tsunami Warning Center.

This story is developing. Please check back for more updates.

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