Crews were called out to the unit block of Second Avenue around 12:30 a.m. Sunday where they found fire was shooting from a home in the middle of the block.
Claymont crews requested help from firefighters in Delaware County to help battle the blaze.
All the residents got out safely, but the family's dog had to be rescued.
There is still no word on what sparked the blaze.
Damage is estimated at $100,000.
Four adults and three children have been displaced and are being assisted by The American Red Cross.