The Brooklyn district attorney, police and fire commissioners announced the indictments on Wednesday. Most of the 18 were charged with arson; all face conspiracy counts.
Authorities say the takedown included all the leaders of the so-called "Borough Park Homicide Squad."
They say the target of the arsons had been stripped of his Latin King status over disagreements with gang leaders.
They say he then stabbed a gang leader's brother. Molotov cocktails were thrown in retaliation for the stabbing.
No one was injured in the fires. But one destroyed a multifamily dwelling where an elderly woman and young children lived.