Lacey Fire District #3 Chief Steve Brooks said two other teenagers who were in the house got out and called 911 when the fire broke out just after 1 a.m. A neighbor across the street also reported the fire.
"That's when we saw the flames stating to come over so we grabbed the hoses and started spraying that car that was parked next door," said Chris Hutcherson.
When firefighters arrived at the house in the 5800 block of 18th Avenue SE, flames were shooting from the roof and windows.
"We saw the kids across the street, they were yelling trying to get into the house to save their friend," Hutcherson said.
Firefighters found the teenager trapped in a back bedroom and brought him outside where medics began performing CPR.
The boy was taken to a local hospital and then flown to Harborview Medical Center in Seattle with severe burns. He's in critical condition in the hospital's burn unit.
"Crews did a great job recognizing that there was an immediate life threatened," said Battalion Chief Bob Petersen.
The house was gutted by the fire, and investigators will begin trying to determine the cause of the fire later Thursday morning.