Sources told the website that Adams was questioned by police at around 6:45 p.m. after being spotted near a Jeep reported to be stolen.
Police searched the vehicle -- which Adams claimed to have bought -- found a loaded gun in the center console and an extended magazine in the trunk.
TMZ Sports reports Adams was arrested on a misdemeanor charge for unlawful use of a weapon and cited for having a high capacity magazine and metal piercing bullets in relation to the incident as he had a permit for the gun, but not issued by the state of Illinois, where his arrest took place.
Adams remained in custody at the time of TMZ Sports' report early Friday (June 24) morning and is scheduled for a court appearance in August.
TMZ Sports reports the owner of the vehicle opted not to press charges, claiming the situation was a misunderstanding.
Adams, who spent his first four seasons with the Indianapolis Colts, signed a one-year deal with the Bears this offseason, reuniting with former Colts defensive coordinator Matt Eberflus, who was hired as Chicago's head coach in January.