State fire investigators say there's too much damage to determine what sparked a fire in Monson Wednesday morning.
It started around 2:30am in a duplex on Route 15.
We're told no one was inside at the time of the fire.
Authorities say heat from the fire melted the siding of Northwoods Medical Building next door.
Route 15 was shut down for a few hours Wednesday morning while crews put the fire out.
Early Morning Fire in Monson Destroys One Building and Damages Another