The boy's father was seriously burned and two other children were rescued from the roof of the burning home.
Investigators believe the fire was intentionally set.
The fire and the subsequent deaths of two family members have stunned the community. Neighbors told ABC7 that it is a very close-knit neighborhood and that the Finnerty family in particular was quite social, hosting the occasional Halloween party. The dad was known around town as an artist and also little league coach. Now the deaths of a mother and her son have devastated all who know them.
As news spread of the early morning fire that killed two members of the Finnerty family, their stunned friends had to see the burned-out house for themselves.
"I just wanted to come down here with my son, Thomas. He has special needs and he's been sent home from school today and he can't fully process any of this," said Cindy Erickson, friend.
Her son, Thomas, was classmates with 11-year-old Garrett finnerty, who died from injuries sustained in the fire along with his mother, 41-year-old Patricia Finnerty.
"Such loss for them," said Cmdr. Kenneth Galinski, Arlington Heights Police Department.
The fire started at 3:30 a.m. on Tuesday. When police and firefighters arrived they found two of the three Finnerty children on the roof and brought them to safety. Inside the house were Patricia and Garrett, each in their bedrooms. They could not be revived. Patricia's husband, Kevin, was downstairs with severe burns. He's currently on life support at Loyola Medical Center.
The house became a crime scene with investigators saying the fire may be arson after suspicious burn patterns were found at the spot where the fire may have started in Patricia's room.
The surviving children are with family.
"Obviously, they're traumatized by the whole situation," said Galinski.>> Neighbors describe the Finnertys as a happy family. Kevin is an artist and had a recent showing of his work. Patricia worked as a counselor full time at Libertyville High School. They released a statement saying, "In the year she worked here they formed bonds with students and staff and she will be deeply missed. Garrett's school is staffed with grief counselors."
"The children and the parents and the teachers and principal of course become a part of a whole unit. So it's a great loss for everyone," said Dr. Sarah Jerome, Arlington Heights School Dist. 25.
Garrett was set to graduate Westgate Elementary School next week. Some of the activities that had been planned to commemorate that next week have been postponed out of respect for the family.