There have been at least eight fires since the end of May in Woodstock, Marengo and Harvard. Authorities say at least two of them were set.
"We have two that are suspicious out of the eight. The other ones, we are working with the local authorities, and the fire departments and the fire marshals to see if there is any evidence that would shed some light if they are or accidental," said Sgt. Michael Cisner, McHenry County Sheriff's Department.
One fire in Woodstock destroyed an antique barn on a cattle farm built around 1860.
"We are checking all of our data bases for arsonists in the area," said Cisner.
Randy Spina lives next door to the antique barn.
"These are 19th century barns. You can never get them back. It is horrible," said Spina.
The other suspicious fire is in Marengo on River Road. Veronica Green has lived on the farm for over a year.
"It couldn't have been just an accident," said Green. "The Historical Society said having a barn like this with two brick silos is different from any other barn around here."
The McHenry Sheriff's Department is also investigating a Crystal Lake barn fire Tuesday night. They are asking anyone to report suspicious activity near barns.