The exact cause of a smoke odor detected in the Upshur County Courthouse Annex Wednesday morning has not been determined.

Employees first detected the smell in the area of the Upshur County Sheriff’s Office at about 11 a.m. Wednesday, prompting a response from the Buckhannon Fire Department, which went through the building and used a ladder truck to try and pinpoint the cause of the smoke.

However, BFD captain Joey Baxa said firefighters were unable to identify the source of the smell. It eventually dissipated on its own.

County maintenance director Greg Harris said the smoke odor may be related to a transformer connected to the HVAC system. According to Harris, firefighters conducted multiple tests and restarted the HVAC to see if the smell would resurface, but it did not.

The county continues to monitor the situation, Harris added.

County administrator Carrie Wallace said the full annex was not officially evacuated because firefighters arrived on scene and quickly isolated the smoke odor to the area of the sheriff’s department.

Main Street was closed between Route 20 and Kanawha Street for more than an hour while firefighters investigated. It has since reopened.