Investigators will likely never know the cause of a million dollar fire that destroyed five townhouses.

Innisfil fire chief John Pegg says the cause of the fire at Friday Harbour is undetermined because of the significant damage. He says the floor and roof of the building collapsed.

Large flames tore through five units at the resort on Feb. 13. Officials say the fire had been burning for some time before firefighters arrived on scene.

A firefighter was injured and taken to hospital. They were treated and released.

Pegg estimates damage to be around $1.5 million.