Firefighters were called at about 7:50 p.m. to the 7400-block of Birch Drive for the reported house explosion.
Multiple fire departments responded to the scene to help extinguish the fire.
Chopper7 flies over Wonder Lake house explosion aftermath
One person was pronounced dead at the scene, the Wonder Lake Fire Protection District said. Two people were taken to hospitals, with one needing to be airlifted. The McHenry County Sheriff's Office said the injured victims are two men, ages 76 and 28.
"Very rare to see fire scenes like this, this is my 30th year in fire service and very few of these calls we see," Wonder Lake Fire Chief Matt Yegge said. "One was flown out via helicopter in critical condition; the second one was transported to a local hospital for further evaluation."
Wonder Lake fire chief gives update on house explosion
The McHenry County Coroner's Office said Monday evening that the person killed had not yet been identified.
An autopsy was performed Monday; the victim was burned, the coroner's office said.
Shock and devastation have rocked the neighborhood.
Drone video taken in the immediate aftermath of the explosion shows the splintered mess on fire.
"It shook the entire neighborhood and knocked things off our walls, and glass debris raining down all the way into our driveway," neighbor Richard Norman said.
Norman lives a street over from the explosion. He said he was watching TV with his family when they heard and felt the explosion.
"We ran directly over there to see if there was anything we could do because we knew people were home at the time," Norman said.
He said he was one of the first people on the scene and immediately jumped in to a pull a person out. Shortly after, the home was engulfed in flames.
"He was in excruciating pain, and all we wanted to do was get the poor man some help," Norman said.
He said those injured are a man and his adult son.
It has made neighbors count their blessings.
"Jesus protected us in that house. If he wasn't there for us, we probably would have been hit too," neighbor Linda Abernathy said.
Neighbors said they heard a mini explosion about 20 minutes after the first one.
The blast also damaged two neighboring homes as investigators assess the great deal of physical and emotional damage left behind.
"I was talking to the neighbor on the next block behind me, and she's in shock," neighbor Dave Schultheiz said. "She's scared."
Neighbors have been picking up debris for most of the day Monday, and an excavator was on the scene.
"The front faade of the house was brick, and there's nothing left of the brick," Kris Gordon said. "Their roof was sitting on top of the neighbor's roof. Her front door is over in this yard over here. Yeah it was a pretty big explosion."
The cause of the initial explosion is under investigation.
"It made me wonder, why would that happen? How did it happen?" Lila Mrowka said.
"I'm shaken up. Shaken up especially since we don't know what caused it yet, you know, if you don't know the cause, you don't know if it could happen to your house," Gordon said.