The four victims, identified as Agus Susanto (50), Regina (18), Nicolas (12) and Alexandro (10) were found by Regina's boyfriend Rico Hastono (18) who visited the family on Wednesday night.
"When I first found them, all four were lying down on the floor that was inundated by 10 centimeter-high flood," Rico said here on Thursday.
Early investigation conducted by the police indicated that the family died due to electrocution.