Tsunami waves have swamped Hawaii's beaches and severely damaged harbours in California after devastating Japan and sparking evacuations throughout the Pacific.
Water rushed up on roads and into hotels on the Big Island and low-lying areas in Maui were flooded as 7ft waves crashed ashore. Large waves also hit the US west coast, shaking loose boats that were not moved in time and tearing apart wooden docks in at least two California harbours.
One man was swept out to sea in northern California while taking pictures of the tsunami waves, sparking a coast guard search. Four others have survived after being swept off a beach in Curry County, Oregon, by a tsunami surge after gathering there to watch the waves generated by the Japanese quake.
"This is just devastating. I never thought I'd see this again," said Ted Scott, a retired mill worker who lived in Crescent City when a 1964 tsunami killed 17 people on the west coast, including 11 in his town. "I watched the docks bust apart."
The waves did not make it over a 20ft break-wall protecting the rest of the city, and no serious injuries or home damage was immediately reported.
Scientists warned that the first tsunami waves are not always the strongest, and officials said people in Hawaii and along the west coast should remain vigilant. Still, the tsunami warning was downgraded to an advisory in Hawaii, and governor Neil Abercrombie said the islands were "fortunate almost beyond words".
"All of us had that feeling that Hawaii was just the most blessed place on the face of the Earth," he said.
The tsunami, spawned by an 8.9-magnitude earthquake in Japan, killed hundreds as it slammed into Japan's eastern coast, sweeping away boats, cars, homes and people as widespread fires burned out of control.
It raced across the Pacific at 500mph - as fast as a jetliner - before hitting Hawaii and the west coast. Sirens sounded for hours on the islands and the west coast before dawn and roads and beaches were mostly empty as the tsunami struck.
President Barack Obama said the Federal Emergency Management Agency is ready to come to the aid of any US states or territories who need help.