LOS ANGELES (CBS SF) – An earthquake with a preliminary magnitude of 6.4 and dozens of aftershocks shook much of Southern California Thursday morning, heavily damaging the town Ridgecrest, according to the USGS and officials .

The quake struck near the town of Ridgecrest about 150 miles (240 kilometers) northeast of Los Angeles. Ridgecrest Mayor Peggy Breeden told CNN that at least five fires have erupted in the town and other buildings have been damaged.

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For continuing coverage of the earthquake, visit CBS Los Angeles.

At least 85 aftershocks of 2.5 or greater were recorded after the earthquake, according to CNN Meteorologist Haley Brink. The largest of them reached magnitude 4.6.

Lucy Jones of the USGS called it a “robust” series and said there is a 50% chance of another large quake in the next week.

Footage from Ridgecrest showed firefighters hosing down flames rising from homes.

“As I understand, we have five fires,” Mayor Peggy Breeden said. “We have broken gas lines.”

There were also power outages in the city of 28,000 residents. The forecasted high temperature is 100 degrees Fahrenheit, the National Weather Service said.

There were no immediate reports of injuries in the Los Angeles area, which is about 125 miles (240 kilometers) southwest of Ridgecrest.

The Kern County Fire Department said it sent search and rescue teams to Ridgecrest, a town of 28,000 people. Fire officials tweeted that evacuations were underway at Ridgecrest Regional Hospital.

U.S. Geological Survey seismologist Lucy Jones told reporters there had been a 4.2. magnitude foreshock before the 6.4 quake. She added that the state’s new ShakeAlert app system failed to send notifications to users.

USGS officials later said the ShakeAlert system had actually functioned as designed, but did not send out an alert to Los Angeles residents because the quake did not reach the threshold for an alert in that area.

Jones said the earthquake Thursday was the strongest to hit Southern California in 20 years. The previous large quake was a 7.1 on that struck in the area on October 16, 1999.

The California Highway Patrol was checking local roadways after there were numerous reports of rockslides.

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People from Las Vegas to the Pacific coast in Southern California reported feeling the temblor. The USGS reported that as many as 21 million people may have felt the quake.

“It almost gave me a heart attack,” said Cora Burke, a waitress at Midway Cafe in Ridgecrest, a town of 28,000 people. “It’s just a rolling feeling inside the building, inside the cafe and all of a sudden everything started falling off the shelf, glasses, the refrigerator and everything in the small refrigerator fell over.”

Video posted online of a liquor store in Ridgecrest showed the aisles filled with broken wine and liquor bottles, knocked down boxes and other groceries strewn on the floor. There was at least one house on fire in Ridgecrest.

Diane Ruggiero, general manager of the Hampton Inn and Suites Ridgecrest in Ridgecrest, told CNN’s Paul Vercammen that the hotel has significant damage.

“The chandeliers are still swinging,” she said five minutes after the quake hit. “The floor rippled.”

Trona, an unincorporated community in San Bernadino County, “sustained varying degrees of damage” but no injuries have been reported, according to San Bernadino County Fire’s verified Twitter account.

The department reported “minor cracks (in buildings); broken water mains; power lines down; rock slides on certain roads” in northwestern communities in the county.

Los Angeles International Airport said no damage was reported on runways. “Operations remain normal,” it tweeted.

Ashleigh Chandler, a helicopter rescue EMT at Fort Irwin said the quake happened as she was getting ready for a July 4th party.

“I was just in the living room getting everything ready, we start to feel the shaking, so then I look up and then the wine bottles start rattling and I thought, ‘They’re going to fall.’

“My sister was in the house and my dog, so we just got everyone outside and then it ended. It was like 15, 20 seconds, maybe. It was pretty good shaking, so I’m out of breath.”

“Everyone’s OK.”

There were reports of heavily damage in Ridgecrest including a roof collapse at a WalMart. There have been no confirmed reports of injuries or deaths.

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