21-year-old Christopher Bray and a 17-year-old were arrested Thursday, and two other minors were arrested Friday.
Officers said the group of four used gasoline to set fire to three homes on Stringtown Road in the Pleasant View Community.
The arsons allegedly happened between April 18 and April 21.
No one was inside any of the homes during the fires.
All four suspects were charged with second-degree arson.
Bray was booked in the Whitley County Detention Center.