Her mother was also injured in the fire Thursday afternoon at the Ravinia Pines Mobile Home Park in the town of New Chicago.
New Chicago Fire Department Chief Joe Eakins said when firefighters arrived, the home was engulfed in flames.
The girl's mother was found in a bedroom and airlifted to the hospital in very serious condition, Eakins said.
Homes on both sides of the trailer were heavily damaged, Eakins said. The state fire marshall is investigating the fire.