A 6.4-magnitude earthquake shook parts of Northern California early Tuesday, causing two deaths and 11 injuries and leaving tens of thousands without power.
According to the U.S. Geological Survey, the quake struck at 2:34 a.m. local time (1034 GMT) in the Pacific Ocean about 15 kilometers from Ferndale in Humboldt County. The town is near the Oregon border, with some 1,300 residents.
The two people who died, aged 72 and 83, suffered coincidental medical emergencies as the quake occurred. In at least one case or possibly both, emergency responders couldn't get to them in time because the ambulances in the area were few and already dispatched elsewhere, according to Humboldt County Sheriff's office.
As of 1 p.m. local time (0900 GMT), more than 70,000 customers in the area were without power, the sheriff's office said, adding that "numerous" gas and water line leaks had been reported.
"This is a Humboldt alert," the Humboldt County Office of Emergency Services wrote on Twitter. "Due to a large earthquake, widespread damage to roads and homes are reported throughout Humboldt County."
"Be prepared for aftershocks," the tweet alerted.
More than 80 aftershocks were reported later Tuesday morning. There was a 13 percent chance of an aftershock of magnitude 5 or larger within the next week, said an expert at the California Earthquake Clearinghouse.
This is the second year in a row a large quake has struck the area on Dec. 20, with last year's 6.2 afternoon temblor hitting off the coast of Humboldt County, according to a report by The San Francisco Chronicle.