One of the victims and families of other victims are now suing the mushroom farm where one of the shootings happened.
The lawsuit alleges the owner of California Terra Garden Mushroom Farm failed to properly respond to previous reports of violent incidents and take steps to prevent others.
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Four workers were killed at the Mushroom farm and three others died at a second farm.
Investigators say the shooter acted after a dispute with his supervisor.
The lawsuit seeks unspecified damages for economic losses related to the deaths and injuries.