The nearby Five Points Fire Company was called to the scene on West Summit Avenue right around 1:30 a.m. on Thursday, April 25.
They arrived to find the home fully engulfed in flames.
Delaware Assistant Fire Marshal Michael Chionchio says it is still early, but he feels good about the direction the arson investigation is moving.
"At this point we have state fire marshal investigators working on some good leads that we have received from people who have been able to talk to us and let us know what is going on," he said.
A 63-year-old woman who was severely burned during the fire remains hospitalized in critical condition. We are told she suffered burns covering 80% of her body.
A second woman inside the home suffered relatively minor injuries.
Authorities say both women were asleep inside the home when he fire started. They add that they have no doubt the smoke alarms inside that home saved their lives.
Anyone with information about this case is asked to call police.