A major fire completely destroyed a house under construction and affected two others on Montreal's South Shore early Thursday morning.

The investigation has been transfered to the Longueuil police (SPAL) arson squad as inspectors do not know why the fire started around 2:45 a.m. at a house under construction on Quinn Blvd. at the corner of Sainte-Foy Blvd. in the Old Longueuil district.

Longueuil firefighters responded to the call and were assisted by crews from La Prairie and Vallée-du-Richelieu.

In total, more than 80 firefighters were mobilized to control the flames, but the intensity of the fire caused the house to collapse.

Two neighbouring houses, one of which was also under construction, were damaged.

No one was injured.