There were no reports of major damage or injuries, but shaking was felt from San Diego County to Simi Valley and out to Victorville and Redlands, according to a U.S. Geological Survey map.
Those living closest to the quake shared videos of a major jolt and rattling that elicited a few screams and sent frightened pets scrambling.
"It was very, very scary," said Kyle Shearer of Highland Park. "It's not my first but it's probably the scariest I've had in a long time."
Pets, residents rattled when 4.4 magnitude earthquake hits LA County
The quake struck around 12:20 p.m. at a depth of nearly six miles. The epicenter was located in Highland Park.
It originally registered as a 4.7 magnitude earthquake, but was shortly downgraded.
"It was a jolt," said Christine Chandler, a professor at Martha Fuerst School of Nursing in Glendale. "And then the building just started to shake violently. It wasn't those nice roll-y ones we get. I had to hold on to the door jamb."
The L.A. county and city fire departments activated earthquake mode to survey the region for damage, particularly to infrastructure. Los Angeles city fire concluded earthquake mode at 1:15 p.m. with no findings of damage.
Some minor damage was reported in Pasadena, only a few miles from the epicenter.
A pipe broke at Pasadena City Hall, sending a stream of water flowing out onto the sidewalk. About 200 employees were evacuated from the building.
Pasadena Fire Department Deputy Chief Anthony James said the water leak was the result of a sprinkler head breaking at the top of the city hall rotunda. Firefighters were eventually able to shut off the pipeline.
And one person was temporarily trapped in an elevator in the building. Firefighters were able to quickly free that individual.
Firefighters were also checking out a report of a broken gas line but hadn't confirmed if it was earthquake-related.
James said he felt the strong jolt.
"I happened to be out driving," James said. "I was parked next to a bus. It felt like the whole ground was going away from under me. I thought what was that? And quickly figured it out."
The department, he said, quickly went into earthquake mode. That meant sending firefighters out into the community to survey for damage. They did not find any other major issues.
Dr. Lucy Jones explains fault system involved in Highland Park quake
Seismologist Dr. Lucy Jones said for many Southern Californians, the shaking felt stronger than other earthquakes they've experienced in recent years - and may have seemed more severe then the 4.4 measurement. That's because many of the earthquakes the region sees hit less densely populated areas and don't feel as strong once they reach the urban core.
"There's a lot of people on top of this earthquake," Jones said. "The other earthquakes you've been feeling .... that's because you were farther away."
It's difficult to pinpoint the exact fault involved, she said.
"This area has a network of buried faults, so it's not something that shows up on the surface. The same network was involved in the 1987 Whittier Narrows quake, but exactly whether it's the same strand, because it's complicated and at depth, we'll never be able to say," Jones said.
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