The men, who were travelling in a white Subaru Imprezza, stopped at the Total gas station to purchase fuel about 12:15 when they were shot.
Their killers escaped in a Nissan motor car.
Deputy Superintendent of Police Colin Milanese, Operations Officer of the St. Andrew North Police Division, said the police could not yet confirm whether the killings are tied to other recent incidents in the area.
However, he pointed out that the gunmen carried out a "very blatant" attack. "They knew what they were doing, and they executed to the end," he said.