The Federal Aviation Administration believes the seven people on board the plane escaped uninjured, spokeswoman Elizabeth Isham Cory said.
"The plane is burning," Cory said.
The vintage plane took off from Aurora Municipal Airport on Monday morning and crashed about 20 minutes later in Oswego, Cory said.
The pilot reported a fire shortly after taking off, said Sugar Grove Fire Chief Marty Kunkle.
"He attempted to make a return to the airport, but couldn't make it so he put it down in a cornfield," Kunkel said.
Firefighters from Oswego, Sugar Grove and Plainfield responded to the crash. Fire officials said they were having difficulty accessing the crash because of wet fields.
The aircraft was made in 1944 and is known as the "Flying Fortress." It is registered to the Liberty Foundation in Miami, Cory said.