A fire that displaced a family of four in a south-end Cambridge neighbourhood was likely caused by an electrical fault, fire officials say.

“Where the main feed comes in … and connects to the house, we found some major arcing and sparking,” Cambridge Fire Department fire prevention officer Eric Robinson told CTV News.

“We believe that’s what caused the fire.”

Flames broke out Sunday morning at the detached house on Lorraine Drive, while its occupants attended a church service.

By the time the fire was brought under control, the main floor of the family home had collapsed.

After spending several hours sifting through the damage Monday, investigators determined that the fire worked its way up from the basement.

Damage is estimated at $500,000.