Elon Musk, the world’s richest man, blamed fellow billionaires George Soros, Reid Hoffman and the ActBlue fundraising organization over recent protests targeting his firm Tesla, citing an “investigation”—though it’s unclear what investigation he’s referencing.

His post has sparked heated debate among his followers, with some supporting his claims and others questioning the lack of evidence.

Last week, approximately 350 protesters gathered outside a Tesla dealership in Portland, Oregon. Earlier in March, nine people were arrested during a heated demonstration at a Tesla showroom in New York City.