The Florida Times-Union reports it happened Wednesday morning at a Jacksonville home.
Jacksonville Sheriff's Office Chief T.K. Waters says officers responded after a woman called to express concern about the man.
Officials say the man refused repeated commands to drop the knife. An officer attempted to subdue the man with a stun gun, but it didn't work. Investigators say the man raised the knife several times, which prompted an officer to fire once, killing the man. No other injuries were reported.
Waters says a SWAT unit responded to the home last month, though that encounter with the man was deescalated.
The races of the officer and deceased man weren't immediately released.
Information from: The (Jacksonville) Florida Times-Union, http://www.jacksonville.com
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