The blaze broke out after 9:00 a.m. in the 300 block of Wildel Avenue in Minquadale.
It took firefighters 20 minutes to get the upper hand.
A woman in her 30s, and two children suffered smoke inhalation and were taken to Christiana Hosptial.
The woman was later transferred to Crozer Medical Center as a precaution.
Investigators determined that the fire started accidently while a child was playing with a lighter.
The damage is estimated to be about $10,000.