Six Nations fire crews had to request the assistance of firefighters from Mount Pleasant as they battled flames at what was initially described as an abandoned church on Mohawk Road north of First Line.
Flames broke out before 4:30 this morning.
Firefighters were unable to go inside the building and the roof has collapsed as they continue to pour water onto it from outside.
In recent weeks, there have been at least 18 fires that were considered arson in the area, prompting the creation of a special task force to investigate them.
The cause of this fire has yet to be confirmed.
There is no word of any injuries.