Arson is believed to be the cause of a stubborn blaze late Monday night in a vacant building on the CN property at the end of St. Catharine Street.
St. Thomas firefighters responded around 11 p.m. and remained on scene until after 3 a.m. Tuesday.
The building was eventually levelled to ensure the fire was completely out.
CN police did attend, with the fire deemed suspicious in nature.
Investigators remained on scene most of Tuesday.
Written by: Ian McCallum