Two half-brothers were busted with loaded guns Thursday night at Bronx Community College after they were ratted out by their sister, whom one had spit at, sources said.

The arrests occurred at about 6:30 p.m. when Jhoni Cruz, 19, was on the grounds of the CUNY school with half-brother Sharma Turner, 26, a student there, a source said.

The men have the same mother.

They were stopped because Cruz’s sister — Turner’s half-sister— filed a complaint a few minutes earlier that she had been threatened by her brother, who had also spit at her, sources said.

Two CUNY officers stopped the men, searched their bags and found two .25-caliber semiautomatics with loaded magazines.