A 6.4-magnitude earthquake shook Northern California early Tuesday morning, leaving thousands of people without power. The quake struck at 2:34 a.m. PT and power outages were reported by 5 a.m., per The New York Times. 

The region most affected was the coastal Humboldt County, per CNN. Over 70,000 county residents had reported power outages as of 9 a.m. 

Widespread damage was also reported. Residents were warned to prepare for potential aftershocks, though the National Tsunami Warning Center said a tsunami was unlikely. There have already been 12 magnitude 3 or higher aftershocks and more are expected until Dec. 27, per a 9:30 a.m. ET forecast from the U.S. Geological Survey. The agency predicts up to 27 magnitude 3 or higher potential aftershocks in the next week, with a “14 percent chance of one or more aftershocks that are larger than magnitude 5.”

The quake also damaged a road near the Fernbridge, “a historic bridge that crosses the Eel River and serves as the primary route for Ferndale residents to reach Eureka, the county’s largest city,” the Times writes. The bridge is currently closed due to cracking in the road and is being inspected for seismic damage, CNN adds.

Tuesday’s earthquake comes exactly one year after a 6.2-magnitude earthquake struck the same county.