"This was a great family, really nice people. Really you know quiet. And yeah, it's really unfortunate," said neighbor Venkat Murali.
The Mundelein Fire Department says they were called to respond to a home engulfed in flames around 12:30 a.m. Monday.
Fire crews say they were looking for a 4-year-old boy who was believed to be trapped. The smoke and flames made it difficult for firefighters.
"Heavy smoke and fire conditions and some of the access into the basement, there was the integrity of the floors were weakened from the fire, and then, the crews couldn't initially make it down the stairwell into the basement, because the stairwell is also compromised," said Mundelein Fire Department Deputy Fire Chief Jeremy Lockwood.
Firefighters made a tragic discovery as they searched the home. Crews found the child dead in the basement.
"There were occupants outside that met our crews upon arrival, reported one occupant of the structure was unaccounted for," Lockwood said. "They didn't locate the individual in the bedroom. The individual was in the basement deceased."
The Lake County Coroner's Office identified the child as Christopher Alfaro-Rodriguez.
The coroner said preliminary autopsy results are consistent smoke inhalation. Toxicology testing, including carbon monoxide levels, are pending on Monday night.
Neighbors who live next door to the family are in disbelief.
"I did see the boy outside playing earlier in the day, and you know, it's just a normal kid," Murali said.
Late Monday morning, crews boarded the home up after investigators spent several hours at the scene.
There were no other injuries. The deputy fire chief says at this point, there are no indications of arson. The cause of the fire is under investigation.