Police recovered five kgs of gold, two motorcycles and mobiles from Bijo, Sijo, Pratheesh and Sindo, all from Kerala.
They were arrested from Tiruchirapalli, police said.
Manhunt was on for two others.
The gang, wearing masks and armed with weapons had waylaid a car and attacked a gold smith Venkatesh and his two workers, when they were returning from Chennai with gold, on January 31, near his house in Ponnaiahrajapuram here.
After inflicting injuries on the workers, the gang fled with the gold bars.