Neighbor Brad Mohlman returned home around 12:30 a.m. to see smoke coming from the house in the 300-block of Normandy Lane. Mohlman tried to go in and help, but the smoke was too thick.
"I ran over there and opened the door and the smoke was so thick, you couldn't get a foot in," Mohlman said.
Police and firefighters were called just after midnight to find heavy smoke billowing from it.
"When our officers arrived there was heavy smoke. Not much flames showing, but heavy smoke from the building," Grayslake Police Chief Phil Perlini said.
Two residents were able to get out safely, but a 17-year-old boy was trapped on the second floor, police said.
Three officers decided to enter the house and made several attempts. They eventually crouched down on the ground and held onto each other to get through the thick smoke.
"They couldn't see, so they were all in constant contact with each other through touch. That's how they went up the stairs," Perlini said. "They could hear him breathing and moaning and groaning as they went up the stairs. They are feeling every step of the way. They went up and finally felt a shoulder, I believe, and they pulled him down the stairs."
The teenager was taken to the burn unit at Loyola in critical condition. All three officers were treated for smoke inhalation at Condell Hospital and are expected to recover.
Two dogs that were in the house died in the fire, but a third dog survived after Mohlman gave it oxygen.
Neighbor Carrie Burns said she hopes the 17-year-old will recover.
"He's always happy, he's always helping around," Burns said. "We do a lot of gardening with his mom, so he's always bringing over barrels of flowers to us. Great kid. Smart. He's amazing."
Firefighters from Round Lake, Libertyville, Gurnee, Newport, Mundelein, Lake Zurich, Spring Grove, Antioch, Countryside, Knollwood helped extinguish the fire.
The Grayslake Fire Protection District is investigating the fire with assistance from the Illinois State Fire Marshal's Office and the Lake County Major Crime Task Force.
"There is some circumstances inside that weren't ordinary. We are just doing our due diligence here to find out what happened," Perlini said.
He did not elaborate on those circumstances. He said since the cause of the fire was not immediately known, investigators called for extra hands to help.
The fire originated in a dryer vent in the kitchen of the home, police said.