The fire was reported at approximately 12:39 A.M. in the unit block of Fairway Road at the Hunters Crossing Apartment complex.
Four families were displaced as a result of this fire. Everyone else in the building was able to return to their units.
The fire marshal's office is continuing to investigate the exact cause.
Investigators say this is the fourth arson in the same complex in three separate buildings. Two were in December and two happened this month.
Deputy Fire Marshal Alan Brown says the other fires were small and put out quickly.
Anyone with information is asked to contact 323-5375 or Delaware Crimestoppers at 800-TIP-3333
