Police found two guns, including a high-powered one, ammunition, duct tape, tie straps, and other items when they intercepted a car bearing a false registration number in Tableland on Monday afternoon.
The police also detained the three male occupants, a 17-year-old minor, a 20-year-old, and a 25-year-old.
The minor is from Robert Village, Tableland.
A report said Tableland police, led by Sgt Ramdial, received information and went to Nohar Road at about 5.30 pm.
The officers, including PCs Ramlal, Ramcharan, Boochoon, and Supersad, intercepted a silver Tiida car with three occupants.
On searching the car, they found an AR-15 rifle with 27 rounds of 5.56 mm ammunition, a Glock 17 pistol with a magazine containing 45 rounds of 9 mm ammunition, the tape, tie straps, masks and fishermen's hats.
There were also several false number plates in the car.
Senior police in the Southern Division have commended the officers, including Cpl Tyson, for their "outstanding and exemplary work" in finding the items and arresting the suspects.
The police referred to them as "priority offenders in the district." They believe the suspects might be responsible for several other offences.
Investigations are ongoing.