Jeana Andrus, 48, Jessica Andrus, 22, Jennifer Andrus, 16, and David Andrus, 50, died from apparent gunshot wounds, and all were family members.
An autopsy shows the father, David Andrus, died after shooting himself. His wife Jenna and two daughters Jessica and Jennifer were each shot in the face.
A source tells the Daily Herald that he stood outside of his younger daughter's bedroom and repeatedly told her to open the door. He then shot her in the face before killing himself.
According to the Daily Herald, he may have been upset about losing his job.
Meanwhile, DuPage County investigators could not confirm exactly what happened inside the home in the 500-block of Oldfield around 3:30 p.m. Tuesday.
Police responded Tuesday to a disturbance at a home and found four people dead inside.
For several hours Tuesday, dozens of heavily armed police officers, many in full SWAT gear, took over the block.