Indiana State Fire Marshal Roger Johnson announced Thursday that following his office's preliminary investigation, "substantial evidence" would be taken to his labs for review.
The State Fire Marshal's office, a Conversation Officer, the Indiana State Police, the Bureau of Alcohol, Tobacco, Firearms and Explosives, the Bridegton Fire Department and the Parke County Sheriff's Department all responded to the fire of the historic Bridgeton Bridge early Thursday morning.
"The bridge has been totally destroyed," Johnson said Thursday at the Parke County Sheriff's Department.
Johnson said he is not sure how the blaze began. He said a projectile being thrown at the bridge can be eliminated, but "everything else is an option."
"There are some indications to lead one to believe it would be an incendiary cause," he said.
The Fire Marshall's Office was investigating the destruction Thursday, but Johnson said, "It's a very large bridge," indicating the investigation would continue for some time.
"We have a large number of accelerant hits," Johnson said.
He was unsure of the number of how many times a fire accelerant was thrown at the bridge and said that fact must be analyzed more due to a treatment used on these older bridges.
Parke County Sheriff Charles Bollinger said because all of the 30 covered bridges in Parke County are solid wood structures they can burn easily.
So, the bridges have been treated with a flame-retardent chemical to reduce the risk.
"This is a very important case to our citizens," he said.