I have no clue where this is, and I refuse to do more than read headlines. So now what?
Walnut Creek is twenty five miles east of San Francisco.
If you commuted from there by car you need to go through a big tunnel and then go over the San Francisco Bay on the Bay Bridge.
It has a 2% black population and traditionally was one of the suburbs where (mostly white) working folks commuted to SF.
This event was almost the equivalent of a Martian invasion for the old-timers that live and shop there.
Inland from Oakland, which is across the bay from San Francisco.