It's not terrorism unless they're trying to push an ideology.
It's organized (assuming there are three suspects) so it would seem to indicate some ideology or motive rather than a disgruntled/crazy individual. They didn't rob a bank or anything. The target doesn't seem to be anything particularly high profile or interesting. I guess it could hypothetically be related to narcotics since it's in SoCal and heavy armament of the individuals.
San Bernadino County is majority white (including hispanics). It's about half hispanic.