An April fire that killed four children when it swept a mobile home in northeastern Indiana began in or near a recliner, but investigators have been unable to determine what sparked the blaze, a coroner's office said.

The Allen County Coroner’s Office said Wednesday that a report from the Indiana State Fire Marshal’s Office found that amount of fire damage the Fort Wayne mobile home sustained made it impossible to prove a definitive cause "to an acceptable level of certainty."

Because of that uncertainty, the coroner’s office said the manner of the deaths of the four children had therefore been ruled as "undetermined."

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The coroner's office had previously ruled that smoke inhalation and thermal burns caused the April 21 deaths of Matthew Damron, 10, Johnnie Mann-Goff, 5, Jefferson Goff, 3, and Rosalynn Goff, 2.

Four adults, including the children's mother, were hospitalized after escaping the fire, which the state fire marshal's report said investigators believe began "in or around the area of a recliner" in the mobile home.

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Fort Wayne, Bloomington, South Bend News

The cause of the Indiana fire which killed 4 children is still unknown.

The mobile home was destroyed, with heavy fire, water and smoke damage, the report said.

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Firefighters brought the fire under control in about 20 minutes, at which time they entered the home and found the children’s bodies.

Fort Wayne is located about 120 miles (195 kilometers) northeast of Indianapolis.