One of the victims, Lomer Johnson, also suffered a blunt head and neck trauma, which could have resulted from a fall or being hit by an object, according to the medical examiner's office.
The other four victims were Johnson's wife, Pauline, and three of their granddaughters, 10-year-old Lily and 7-year-old twins Grace and Sarah.
All the deaths were ruled accidental. Stamford fire officials said Tuesday that embers in a bag of discarded fireplace ashes started the fire.
Homeowner Madonna Badger, an advertising executive who is the girls' mother and the Johnsons' daughter, escaped from the fire, as did Michael Borcina, a friend and contractor working on the house. Borcina, 52, was released from Stamford Hospital on Wednesday morning, a spokeswoman said.
As flames shot from the home, Badger climbed out a window onto scaffolding, screaming for her children and pointing to the third floor.
Firefighters went into the house twice trying to rescue the victims, but were forced out by the blaze's intensity. Four firefighters were injured, including a captain who suffered second-degree burns on his face, officials said.
Borcina and Johnson tried to save them as well. One of the girls, found dead just inside a window, had been placed on a pile of books, apparently so Johnson could reach in and grab her after he jumped out.
Instead, authorities say, Johnson fell through the roof outside the window and was found dead in the rear of the house.
He and his wife, both of Southbury, had been visiting their daughter for the holidays. -- AP