Actually, there were two such incidents, I believe. One was the shelling of an oil refinery in California and the second was of Ft. Stevens, Oregon near the mouth of the Columbia. There was also an actual bombing: a float plane launched from a Japanese sub dropped a couple incendiary bombs near Brookings, Oregon. They failed to set the forest ablaze.
No one was killed in any of these attacks. At Ft Stevens, all the shells missed hitting any of the shore batteries. The batteries didn’t return fire because of an error by the range detector operator who mistakenly calculated the sub was out of range.
Japanese attack on Ellwood refinery
On looking these up on Wikipedia ([url="http://en.wikipedia.org/wiki/Attacks_on_United_States_territory_in_North_America_during_World_War_II for those interested), it seems there was an attack on a lighthouse on Vancouver Island the day before the attack on Ft Stevens. I was unaware of that before now. Also, despite the title of the Wiki page, Vancouver Island is not US territory.
There were also some similar incidents on the East Coast and in the Caribbean involving German U-boats. I don’t know much of the details but there’s stuff about them in the Wiki page linked above.