It is happening. I looked into it briefly and it is happening in Europe, but the interesting part is that they haven't been able to determine which type of orca is doing the attacks.
Orca's are essentially tribal. Different parts of the world have different types of orca, but they're not really a different species. It's more like how we have different 'races'. Certain geographically defined groups have certain identifiable characteristics. And the orca's doing the attacks don't uh... fit the description... of the orca's that are normally found in the region. Which is pretty interesting in itself, it could be a rare trait, a chromosomal disorder, or interbreeding. Interbreeding between orca groups is also pretty rare because they're kind of racist against eachother and quite territorial, not to say it doesn't happen though.