Three teens have been arrested near the Victorian border after they allegedly tried to steal a car at gunpoint

Three teenagers have been arrested near the Victorian border after allegedly attempting a gunpoint carjacking in an SA suburb.

Three teenagers have been arrested near the Victorian border after one tried to allegedly steal a car at gunpoint at a western suburbs business late on Saturday.

The trio were captured on security cameras as they crossed Port Road on the weekend, 7NEWS has reported.

Would-be thieves attempted to steal a car at gunpoint at an Alberton car wash. Picture: 7NEWS

They allegedly then attempted to steal the car of a 21-year-old man at an Alberton car wash.

One of the trio allegedly pulled out a gun but the victim acted swiftly, quickly driving away and calling triple-0.

Following an investigation, police intercepted the teenagers on a bus to Bordertown, near the Victorian border, on Monday morning.

A 19-year-old Victorian man has been charged with firearms offences and assault while two other teens were arrested.

A 17-year-old Queenstown boy and a 15 year-old Kilburn boy were arrested for unrelated matters.

They have been refused police bail and will appear at the Mount Gambier Youth court on Monday.

Police say the investigation is continuing and being conducted by Operation Meld, launched to tackle youth crime gangs.