Police say the victims, both men, were shot at the entrance of Club Dream on Canal Road just after 4 a.m. Friday.
One man was reportedly shot in the abdomen and is in stable condition at Brookhaven Memorial Hospital. The other, authorities say, was shot in the arm and was treated at Stony Brook University Hospital.
The shooting may have stemmed from a dispute over Halloween costumes, which partygoers were wearing for a club-sponsored party.
The suspect fled the scene, and no arrests were immediately made.
Sources say identifying the suspect was complicated, because the club goers were all wearing costumes.