(CNN) -- A Michigan man arrested at Chicago's O'Hare International Airport on Saturday after a loaded handgun was allegedly found in his carry-on bag has left jail after posting bond, a representative at the Cook County Jail said Sunday.
Francis Cook IV, 67, of Delton, Michigan, is charged with a felony weapons violation, according to Chicago Police Department spokesman Darryl Baety.
An officer with the Transportation Safety Administration spotted the .380 semiautomatic handgun during screening late Saturday morning, Baety said.
The gun was fully loaded, with five rounds in the magazine and one in the chamber, he said.
Cook's son said Sunday that his father never intended to take the gun on board. "He feels completely stupid about it, I'm sure," Jason Cook told CNN on Sunday night.
Jason Cook said his father is a recently retired truck driver accustomed to taking a bag with his loaded gun on driving trips, and that he had unthinkingly taken the same bag for a trip to Dallas, Texas.
Jason said his father has a license for the gun and that he was headed to Texas for a meeting of owners of a professional women's football team called the West Michigan Mayhem.
Cook was detained and taken into police custody on Saturday, the Chicago police's Baety said.
A spokesman for the Transportation Security Administration, Luis Casanova, said Sunday that the group's incident report made no mention of resistance from Cook. "Any kind of commotion would have been duly noted," he said.
The representative would not provide a name because the person was not authorized to speak to the news media.
On Sunday night, Jason said his father was on his way home after posting $25,000 bond.
CNN's Doug Rink contributed to this report.