The fire broke out around 7 a.m. at a home near Summit and Roosevelt Roads in Unincorporated Villa Park. A woman, her two teenage sons and a niece were all killed.
Neighbors called firefighters who arrived to find smoke billowing from the single story ranch house. Inside, a relative of the victims says authorities found the bodies of 37-year-old Ursula Nailor, her two sons, 16-year-old Darnell Holt and 13-year-old Daniel Nailor, as well as her 19-year-old niece, Dominique Robinson.
Law enforcement sources say all four were shot before the killer set the house on fire. Investigators believe the killer may then have taken his own life.
According to sources, police were going to question Ursula Nailor's boyfriend, Cedric Anderson, 42, at a home in Dolton. But instead they found Anderson dead of an apparent self-inflicted gunshot. They also found a .357 magnum revolver, the possible murder weapon, and a note he had left.
On Tuesday afternoon, investigators combed through what is left of the home. Dogs were helping officials sniff out gas or some other accelerant, which may have been used to help the fire spread quickly and also may be a sign of arson.
"This is considered a suspicious fire," Dawn Domrose, spokesperson, DuPage County Sheriff's Office. "Because of the suspicious nature, they look for any sense of any type of accelerant."
Nailor worked as a bus driver with Falcon Transportation for the last four years. When she failed to show up for work Tuesday morning, her employer called to check on her.
"She talked a lot about her kids. Her kids were kind of older, 15, 16, something like, I think she had two kids. She cared a lot about her kids," said Ed Peterson, victim's employer.
"I am horrified and shocked at what happened, because originally they said there was no one occupying the house right now, and then they told us they found four bodies," said Ann Bendera, neighbor.
Darnell Holt was a student at Willowbrook High School, where he played football and was on the wrestling team. The principal of the high school is scheduled to hold a news conference Wednesday. Officials are planning on providing grief counselors for the entire district.
Several dozen of Holt's classmates held hands and prayed during a vigil Tuesday night. They light candles, hugged and shed tears.
"He was funny, athletic," said Kyle Rushing, friend. "He was very competitive, a great wrestler and an amazing friend. And I'm going to miss him."
"I just can't believe this happened. It's like unreal. Everyone is like, when will this dream end, it's not happening," said Danielle Holden, friend.
"We were a big family and now one of the members is...It hurts," said Giselle Carter, friend.
The coroner's office has not yet officially identified the victims.
The investigation is ongoing.