Pair targeted with gun threat and firebomb

Two people have been threatened with a gun and had a fire bomb flung into their front yard in Adelaide.

An argument broke out between the two people at their Lockleys home and a visiting man and woman they knew on Tuesday night, with the visitors threatening the other duo with a gun before driving off, police say.

A few hours later a molotov cocktail was thrown into the front yard of the home, starting a small fire, but nobody was injured in the incidents.