A resident of Ionia County stands in ash left by Whites Bridge after it was burned down in an arson fire on Sunday, July 7, 2013. The historic bridge was Michigan's oldest original-construction covered bridge built in 1867. (Lauren Petracca | MLive.com)

Erected in the late 1860s, the historic Whites Covered Bridge was destroyed by an arson fire on Sunday, July 7, 2013.

UPDATE: Finding an official cause could take weeks, investigators say

IONIA COUNTY, MI — Belding Fire Chief Gregg Moore isn't ready to call the blaze that destroyed the historic Whites Bridge early Sunday an arson.

Instead, Moore said officials face the daunting task of investigating a "suspicious" fire that will be examined Monday with the help of a state police fire marshal.

The charred remains of the historic Flat River crossing, by some accounts built in 1867, now sit in the very waterway the structure loomed over for decades.

Moore said that complicates matters, and makes it difficult to even preliminarily say the fire was in fact arson, as police initially indicated.

"Usually when they come out, the first thing we're going to look for is can we determine the origin," he said. "With all that laying in the river, that's going to be pretty hard."

Related: History in the rubble: How arson-struck Whites Bridge became a West Michigan landmark

Firefighters were alerted to the fire around 5:15 a.m. Sunday, after a newspaper deliverer spotted the bridge in flames.

By the time crews arrived at the scene, on Whites Bridge Road about 8 miles northeast of Lowell in Keene Township, the structure had all but been destroyed.

The blackened remnants of the 120-foot bridge eventually fell, smoldering, into the river. It was the oldest covered bridge of its kind in Michigan.

"After two hours of burning," Moore said, "there wasn't much left."

Potential culprits range from fireworks to human action, but because the bridge's remnants now are moored in the river, it is difficult to say what happened.

Police initially deemed the blaze an arson, but Moore disputed that claim.

Related: Whites Bridge arson: Emotional scene in Ionia County after historic covered span burns

"I would call it suspicious at this point, because there's no reason that the wood bridge should catch fire," Moore said.

"There's no sources there that we would be looking at other than sources induced from the outside."

Moore said investigators will follow up with potential witnesses, including a resident who told MLive he heard an explosion and saw flames two hours before crews arrived.

Moore said the man, who did not call authorities because he thought others already had, might be able to give officials a clearer picture of the moments leading up to the fire.

"There wasn't many people around at the time," Moore said.

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