Well It’s not that uncommon to haul bee hives around California. They move them around to whatever crop needs pollinating that time of year. So they’ll move them to the almond orchards when they’re in bloom, then the tomato fields, then the orange trees, or whatever. As for them being killer bees, maybe they took over the hive and the beekeeper didn’t notice until it was too late.
Not just in California. Googling, I found an incident in May involving a truck carrying 15 million bees in Maine (though they mostly stayed on the trailer) and one from August 2023 involving five million bees in Ontario, though those escaped. A dozen or so beekeepers worked together to capture the bees.