A monster earthquake off the coast of Northern California has triggered a tsunami warning for millions of Americans.
The San Francisco Bay Area has been told to expect enormous waves at 12.10pm local time.
Residents are being told to rush inland and take cover before the waves hit.
The 7 magnitude earthquake hit on Thursday morning around 50 miles from California's coast.
An aftershock was then felt moments later.
Tsunami warning issued across California and Oregon
A tsunami warning is in effect from the Davenport coast to the Oregon-California border, including the San Francisco Bay area.
The National Weather Service forecast tsunami activity to start around 11:10 a.m. PST in Fort Bragg, 11:20 a.m. in Crescent City then 12:10 p.m. in San Francisco.
In Oregon, tsunami activity is predicted to start at 11:20 a.m. in Port Orford, 11:25 a.m. in Brookings then 11:40 a.m. in Charlestion.
Residents are advised to evacuate inland or to higher ground, move out of the water and off the beach and do not return until local emergency officials declare it safe.
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The tremor struck near the coastal town of Eureka at 10:44 a.m. PST on Thursday, promoting a tsunami warning from the National Weather Service.
It was initially reported as a 6.6 quake but was quickly upgraded by USGS.