Brinley Snyder, 4, was pronounced dead at Lehigh Valley Hospital-Cedar Crest in Allentown on Thursday afternoon. Her brother, Connor, 8, died shortly after.
First responders were called to the house on the 2400 block of Route 143 in Albany Township around 4 p.m. Monday.
Once inside, they found the 8-year-old boy and 4-year-old girl unconscious Both were flown to the hospital.
The coroner's office said Friday that autopsies will be done to determine the cause of death.
The deaths are being investigated by the Pennsylvania State Police-Hamburg Barracks with assistance from the Berks County District Attorney's Office.