Three bodies were found inside the apartment where a "suspiciously fast'' fire spread and gutted two units.
Police say the man stabbed a 46-year-old woman in the heart and strangled a 70-year-old woman before dying of smoke inhalation.
Media reports have identified the two women as the man's wife and mother.
A three-year-old boy, reportedly the man's son, was found at the scene Saturday evening with a note in his hand.
Police have determined an accelerant was used to start the fire.