The woman was rushed to Roseland Hospital first, but it took several hours before firefighters found the boy.
His body was found in the attic of the home near 107th and South Prairie.
Firefighters had already put the fire out and investigators were inside, when they found the body of the boy.
"The child was probably five feet under where the window branches out," said fire commissioner Robert Hoff. "There is a place called a knee wall and the child probably crawled up in there and was in between the rafters."
Aside from being hidden from view, Hoff said when firefighters arrived on the scene shortly before 10 a.m. they had information that a woman lived there, but that was it.
"They knew the woman lived there and that's when the chief requested help because of the conditions of the fire, they couldn't make the basement right away," Hoff said. "(They) had a hard time getting into the first floor because of the conditions and once they got water on the fire they were able to go in and do the search."
Keosha Smith lives two doors down from the now burned out home.
"The firemen were here and they were breaking the windows," Smith said. "They couldn't get her out through the front. They had to get her out through the back."
Once rescued, fire officials say the 66-year-old woman was unconscious and had to be resuscitated before being rushed to the hospital. It was only during investigators search of the building several hours later that he was found along with one of two pets who also died in the fire.
Terrance Coleman, the boy's cousin, arrived on the scene trying to find out what happened. He said the woman in critical condition is the boy's grandmother.
"He was a good kid," Coleman said. "He liked to smile and jump around and play and just enjoy everything he do."