The incident took place in the 7400-block of 173rd Street just before 11:30 a.m.
Investigators said the suspect is the husband and father of the four women shot and killed.
The Cook County Medical Examiner identified the victims as Majeda Kassem, 53, and her three daughters, 25-year-old twins, Halema and Zahia, and 24-year-old Hanan Kassem.
“It’s a tragedy,” Village Manager Pat Carr said. “Not only for the family, but all the surrounding neighbors that are there.”
Police said when they arrived on the scene, the suspect, who has not been identified, was found uninjured inside the home with a gun.
It wasn’t immediately clear if he was the same person who called 911.
The man is in custody with charges pending.
Authorities said the incident is domestic is nature, and does not present any harm to the general public.
Residents have been asked to stay away from the area.
The news was disturbing for those who live nearby and knew the family.
“My daughter knows them,” neighbor Charlotte Vaitkus said. “She went to school with the oldest son, and she employed the twin sisters. She always talked about how they were all very intelligent, and they had very high goals in life.”
Tinley Park police will give more insight into the incident at 11 a.m.
Sun-Times Media contributed to this report.
You can contact the Illinois domestic violence hotline at 1-877-863-6338 click here for more information.