MINNEAPOLIS (WCCO) — The cause of the north Minneapolis duplex fire that claimed the lives of five children last Friday is being classified as “undetermined,” according to the Minneapolis Arson Unit.

Authorities released the findings on Wednesday, saying while the cause can’t be proven “to an acceptable level of certainty,” there is nothing to indicate this was anything other than an accident.

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They say there is no indication of arson, though they will continue looking into possible causes.

The fire started at a duplex on the 2800 block of Colfax Avenue North shortly after 5 a.m. Friday. When firefighters arrived, they found heavy smoke on the second and third floors but that quickly changed to fire.

Three children died at the scene while two others were taken to the hospital, where they later died.

Two other children at the home survived, along with the children’s father, Troy Lewis.

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The names of the victims, three girls and two boys, were released Tuesday by the Hennepin County Medical Examiner. They were identified as Mary Lewis, 6; Troy Lewis V, 3; Christopher Lewis, 8; Fannie Lewis, 4 and 18-month-old Gwendolyn Lewis. Authorities said Fannie and Troy Lewis V died at North Memorial Medical Center, while Gwendolyn, Mary and Christopher Lewis were found dead at the scene.

Authorities said the causes of death among the five children vary, but most are from smoke inhalation with a combination of carbon monoxide poisoning from the fire. The Medical Examiner said Fannie Lewis died from inhaling products of combustion from the fire.

This is the second major fire in the city in as many months. On New Year’s Day, an apparent explosion and fire destroyed an apartment building near downtown Minneapolis on Cedar Avenue. Three people died.

Minneapolis has suffered at least eight fire deaths already in 2014.

Donations for the Lewis family can be made out to MFT 59, and all checks can be made out to “in care of the Lewis family.” The phone number is 612-529-9621.

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The Garrett family, who lived on the first floor of the duplex, also lost their home in the fire. Donations can be made at BMO Harris Bank “in care of the Garrett Family.” The phone number is: 612-238-8700.