The Investigative Committee said the man argued with the factory's new owner and then opened fire with a shotgun.
Moscow police denied earlier reports that the man took several people hostage but confirmed that he has holed up on the premises.
Ilya Averyanov called the Business FM radio station and said he was defending himself against a "gang" that colluded with Moscow prosecutors to seize his property.
Averyanov said he will "fight 'til the end."
There was no immediate comment from authorities on his allegations.
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