Seven people have died after their plane went down in dense fog upon returning from the NCAA basketball championship.

The Cessna 414 went down near the Bloomington airport in Illinois just after midnight on Tuesday 7 April, according to the Federal Aviation Administration.

McLean County Sheriff Jon Sandage said the coroner pronounced all on the board were dead.

A search was launched and a Bloomington police officer discovered the wreckage in a field northwest of the airport, the office said. "It was determined that there were no survivors," it said in a statement.

It's believed that dense fog may have been a factor in causing the crash, according to WMBD-TV.

Carl Olson, director of the airport did not say if the pilot indicated experiencing any trouble or make any alterations in flight.

"My daughter's husband and three other men and the pilot went to the NCAA game last night and they were flying back and I guess the weather was bad in central Illinois. It was foggy," said Scott Barrows, the father-in-law of the Cessna 414's owner, Scott Bittner, 42, who was among the victims, the Chicago Tribune reported.

"They were supposed to land around midnight. My daughter was called at 4 am. There was no contact," he said. "It has been confirmed they are dead."

Scott Barrows said his son-in-law, who owned the aircraft and regularly employed the pilot, whom he described as "very experienced".

Also among the dead were Terry Stralow, a partner in a popular bar in Bloomington-Normal.