The security official, speaking on condition of anonymity, told Anadolu Agency that a grenade had exploded accidentally as the soldiers stood guard in the southeastern Yuksekova district where the Turkish Army's 3rd Division Command is stationed.
Two wounded soldiers were transferred to Yuksekova State Hospital.
The governor of Hakkari will hold a press conference later Wednesday to explain the details of the incident.
Since mid-July, numerous clashes between Turkish security sources and the terrorist PKK group have occurred in the southeastern parts of Turkey.
The PKK -- also designated a terrorist organization by the U.S. and the EU -- renewed its armed campaign against the Turkish state this summer.
Since July, more than 150 members of security forces have been martyred while, according to the government, more than 2,000 PKK terrorists have been killed.