Ridgecrest, California CNN  — 

Lashane Metcalf Williams and her husband, like so many across the country, were sleeping in, taking advantage of the Fourth of July holiday.

Then their apartment building began to shift and shake violently. Pictures flew off the wall.

It was 10:33 a.m local time on Thursday, and the largest earthquake to strike Southern California in nearly 20 years had just hit – a magnitude 6.4 temblor centered near Williams’ home in Ridgecrest, California.

For a moment, Williams couldn’t move, saying she was “paralyzed with fear.” Then she and her husband heard their 1- and 3-year-old sons and they ran for them – as the building continued to roil from the quake.

By the time they got to them, the earthquake was over. But the magnitude of what had just happened near the city of 28,000 in the remote Searles Valley, 150 miles north of Los Angeles, was just beginning to play out.

For about a minute, residents say, the city shook. Light fixtures swayed, windows rattled and televisions banged against walls. Inside convenience stores, aisles were flooded with broken liquor bottles and food that had fallen from the shelves.

Items knocked from the shelves inside State Bros. Markets in Ridgecrest, California.

Across town, Kimberly Washburn was directing a children’s July Fourth program. Sixty-five children were on stage, while their parents looked on from auditorium seats, when the quake hit. The children started screaming.

“It was terrifying,” Washburn said.

Firefighters battling a house fire in Ridgecrest, California.

In the first few hours after the quake, firefighters worked to put out fires at several homes and checked on residents who had been injured by broken glass, debris and falling shelves. Police, along with city officials, scrambled to evacuate patients from the Ridgecrest Regional Hospital and worked to keep calm residents of a senior living center.

“We have more calls than we have people,” Kern County Fire Chief David Witt told reporters.

Over 160 emergency calls in the area caused an “extreme backlog” after the quake, Witt said later on Thursday.

And Mayor Peggy Breeden begged her community members for help.

“If you are okay and you are near a neighbor and do not know where they are or what condition their home is or them, please knock on their door and find out,” Breeden said. “We are a city of 28,000 very close-knit people.”

‘I was fearing the worst’

There were more than 150 aftershocks of magnitude 2.5 or greater in the hours after the earthquake, according to USGS Seismologist Robert Graves. It is a higher than normal number, but not unprecedented, he said. The largest aftershock was a 4.6.

“We are preparing for the worst, hoping that we don’t get any severe aftershocks,” McLaughlin said.

Ridgecrest and nearby communities reported some damage in buildings and roadways but no major injuries.

“It was very strong. I was worried we were going to have collapsed buildings or something to that effect,” Ridgecrest Police Chief Jed McLaughlin said.

“I was fearing for the worst and I’m glad that it didn’t happen.”

A crack in the road is seen near Ridgecrest , California on Thursday, July 4, after an earthquake in the area.

‘No one wants to go inside’

As the aftershocks continued to rock Ridgecrest, families fled their homes, with many taking refuge in a Walmart parking lot.

Williams, her husband and their two sons were among those who made their way there.

Her husband, Caleb Metcalf, said families feared the buildings would collapse if they stayed indoors.

“No one wants to go inside,” he said. “Out in the open, in the parking lot, there’s nothing really to just fall and crush you.”

Cindy Holbork also went to the parking lot. She had been in the shower when the quake hit.

“The shampoo and everything flew all over the place and the doors were opening and shutting,” she told CNN affiliate KGET. “The water went off for a minute.”

She and her husband rushed to get their SUV out of their garage and drove around the streets before parking outside Walmart.

“We are waiting for that big one to hit, hoping it doesn’t,” her husband, Mike Holbork, said.

CNN’s Paul Vercammen reported from Ridgecrest, and Nicole Chavez reported and wrote from Atlanta. CNN’s Steve Almasy, Amanda Jackson and Darran Simon also contributed to this report.