The four IS militants were "neutralised" after they responded to a warning shot fired by security forces and then opened fire themselves, Turkish security sources told AFP.
Security forces in an armoured vehicle had fired the warning shots after seeing suspected IS militants driving towards them in two cars in the Oguzeli district of Gaziantep, the sources said.
The Turkish security forces opened fire on one of the cars but the remaining suspects in the other vehicle fled the scene.
Turkey has been on the hunt for IS extremists after a series of deadly attacks including the October 10 bombings in Ankara which killed 107 people.