Windsor Police are busy investigating another arson Friday morning.

Fire broke out in a vacant house at 1653 Benjamin Ave. Thursday night.

The fire ripped through the attic of a vacant duplex for nearly three hours before fire fighters could bring the blaze under control, according to fire prevention officer Lee Tome.

"Upon arrival crews found fire coming from the second floor of a vacant duplex. The fire was determined to be intentionally set," said Tome.

The damage is estimated at $100,000, according to Tome.

One firefighter was treated for exhaustion fighting the blaze.

He says there does not appear to be any connection between the house fire and the incident at a used car lot early Thursday morning, when four vehicles were set on fire using gasoline and road flares, causing $15,000 damage.