Three pairs of army uniforms were found inside the bag near Mamun military station; it also had 'Jammu' written on it.
The army, police and SWAT commandos have launched search operations.
High alert in Pathankot
Punjab saw two major terror attacks in two years
Earlier in May, more bags were recovered which carried two mobile tower batteries.
Punjab has witnessed major terror attacks in the last two years. In July 2015, three terrorists in the guise of armymen stormed a police station in Gurdaspur and left seven dead.
In January last year, four terrorists raided an airbase at Pathankot; seven security personnel were killed in the attack.