Investigators say a man killed a woman and the teenager, then turned the gun on himself.
The bodies were discovered in Wilmette on Monday afternoon at a house in the 800-block of Greenleaf Avenue.
Wilmette police will hold a news conference on Tuesday morning at 9:30 and more details are expected to be released about the circumstances that led up to the shooting. It is unclear if there will be a statement from First Presbyterian Church of Wilmette which is next door to the house where the double murder/suicide took place, claiming the lives of three Church members.
"There's just no way to explain anything of this nature," said John Nye, church member.
Members of First Presbyterian Church of Wilmette were still stunned as they left a special prayer service for three fellow members who were killed in an apparent murder/suicide.
Wilmette Police say a man, woman, and teenage boy were found dead and preliminary investigations indicate that the man shot the two others and turned the gun on himself.
"They seemed very united, a very good family," said Steven Felt, church member.
Forensic crews stayed at the home for hours after police were initially called at 11:30 a.m. for a well-being check. They eventually they broke down the door, finding the bodies inside.
"They all looked like C.S.I. I mean you had people walking around with their boots covered up and picking things up and putting them in a black bag and going in and out of the building," said Patty Jane Pelton, neighbor.
According to neighbors, the house is the parsonage of the church and the three people who lived there were church members. The woman was employed as church support staff. The teenage boy was a senior at New Trier High School and a leader in his boy scout troop.
"It's shocking. We don't know too much about it. We just wanted to come express our respects to the family," said Stephanie Foye, church member.
The New Trier superintendent says the boy was well known and loved at school. He had just been accepted into a college. Crisis counselors will be on hand for students and staff on Tuesday at the high school.