What happened?
The epicenter of Thursday's shaker occurred in what's known as California's "earthquake country" because it's where three tectonic plates meet.
The temblor was the most powerful to rattle the state since a 7.1-magnitude quake hit Ridgecrest in 2019.
People along nearly 500 miles of the California and Oregon coasts were under the tsunami warning for about an hour. It was lifted after no major waves arrived.
Where did the earthquake hit?
The quake struck at 10:44 a.m. west of Ferndale, a small city in coastal Humboldt County, about 130 miles from the Oregon border, the U.S. Geological Survey said.
The shaking knocked items off grocery store shelves and sent children scrambling under desks at schools.
It was felt as far south as San Francisco, some 270 miles away, where residents described a rolling motion for several seconds. It was followed by multiple smaller aftershocks. There were no immediate reports of major damage or injuries from the quake.
"The damage was mostly broken glass, some windows, pictures off walls ... had some water damage, street lines breaking, the water company was on that right away but no injuries reported," said Rick Nicholson with the Ferndale Volunteer Fire Department.
The tsunami warning issued shortly after the quake struck spanned from the edge of California's Monterey Bay north into Oregon.
"It was a strong quake. Our building shook. We're fine, but I have a mess to clean up right now," said Julie Kreitzer, owner of Golden Gait Mercantile, a store packed with food, wares and souvenirs that is a main attraction in Ferndale.
The region - known for its redwood forests, scenic mountains and the three-county Emerald Triangle's legendary marijuana crop - was struck by a magnitude 6.4 quake in 2022 that left thousands of people without power and water. The northwest corner of California is the most seismically active part of the state because it's where three tectonic plates meet, seismologist Lucy Jones said on the social media platform BlueSky.
Gov. Gavin Newsom signed off on a state of emergency declaration to quickly move state resources to impacted areas along the coast. State officials were concerned about damage in the northern part of the state, Newsom said.
Crews in Eureka, the biggest city in the region, were assessing if there was any damage. Eureka Mayor Kim Bergel, who works at a middle school, said lights were swaying and everyone got under desks.
"The kids were so great and terrified. It seemed to go back and forth for quite a long time," she said. Some children asked, "Can I call my mom?"
This quake was a strike-slip type of temblor that shifts more horizontally and is less prone to cause tsunamis, unlike the more vertical types, said National Weather Service tsunami program manager Corina Allen in Washington state.
The Associated Press contributed to this report.