Rapper Polo G Arrested for Carrying Concealed Firearm in DTLA

Polo G is in trouble because of guns once again ... the rapper was arrested on another weapons charge.

Law enforcement sources tell TMZ ... the rapper was arrested on Monday afternoon in Downtown L.A. after cops say they found him carrying a concealed firearm, a felony.

We're told Polo G was a passenger in a car that was pulled over, though it's not clear exactly why. In any event ... cops say after searching the car they found the firearm. We're told a male juvenile was also arrested and booked on the same charge.

The arrest comes nearly 3 months after his album release party ... when he was arrested in Miami after allegedly attacking a cop. Cops there say they also found 2 handguns inside a bag after the Cadillac he had been riding in was pulled over for blackout-tinted windows.

Polo G was also a passenger during that stop. Cops said he became combative and they struggled to get handcuffs on him. The escalation left 1 cop injured.