EXCLUSIVE

7/21 7:30 AM PT -- Bail was just set at $17k.

7/21 6:47 AM PT -- Police say Offset had 3 handguns in the vehicle and $107,000.

3:46 PM PT -- Offset was hit with 4 charges ... possession of a firearm by a felon, possession of a weapon during a crime -- both felonies -- and possession of marijuana (one ounce or less), and an improper lane change ... both misdemeanors.

The rapper was apparently pulled over for the lane change, not for tinted windows.

Offset is behind bars in Georgia after cops pulled him over and allegedly discovered at least one weapon.

Sources tell us the Migos rapper was traveling just outside Atlanta Friday when the vehicle he was in was pulled over for tinted windows. A witness tells us officers then discovered at least one gun in the car ... a big no-no for Offset, who is a convicted felon.

Offset and Cardi B welcomed their daughter, Kulture, into the world earlier this month ... we're told neither Cardi nor the baby were in the vehicle at the time of Offset's arrest.

We're still working to confirm details with law enforcement.