ISILAMIC GUN BLAST IN US SOIL

Ali Muhammad Brown claims he killed these four men as "vengeance" for the U.S.'s military action overseas. Were these murders acts of terror on U.S. soil? Greta Van Susteren investigates.
TUNE IN to 'Greta Investigates: The Lone Wolves of Terror,' tonight at 7p ET.

TONIGHT: Don't Miss 'Greta Investigates: The Lone Wolves of Terror'

In this Fox News special, we examine other cases of 'lone wolf' terrorism in the United States and the UK.

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