A fire team was a military unit that consisted of two to four infantry soldiers. Two fire teams equaled a squad.
As the USS Defiant prepared to go into the Gamma Quadrant to intercept the Tal Shiar/Obsidian Order fleet in 2371, Lieutenant Commander Michael Eddington brought a security detachment along, and issued phaser rifles to each of the fire teams aboard. (DS9: "The Die is Cast")