The blaze that killed five young siblings on Valentine's Day was an accident, but the cause is undetermined.
The ruling Wednesday by the Minneapolis Fire Department found that the source of the fire could not be "proven to an acceptable level of certainty," though authorities said it does not appear to be arson and will continue looking into possible causes.
A source with knowledge of the investigation told the Star Tribune that the Fire Department was examining a space heater on the second floor as a potential cause, and an investigator was seen Wednesday removing part of a heating device from the burned-out north Minneapolis duplex.
Troy Lewis, the father who survived the fire, has said a space heater he bought recently may have sparked the blaze.
Investigators from the city, the state and an insurance company combed through the site at 2818 Colfax Av. N. all morning Wednesday, snapping pictures and collecting evidence.
"There is nothing to indicate that this is anything other than an accident, and there is no indication of intentional acts," the department said in a statement later in the day.
On Friday, five children died and two survived when the duplex went up in flames shortly after 5 a.m. The children — Christopher, 8; Mary, 6; Fannie, 4; Troy, 3, and Gwendolyn, 18 months old — died from fire-related injuries.
Lewis described his frantic efforts to rescue the children, wailing: "I wanted to get all of my babies. All of my babies."
