The clashes with militants from the Kurdistan Workers Party (PKK) broke out in the Uludere district of Sirnak province at a check point near a prison, the security sources said.
The autonomy-seeking PKK has waged a three-decade insurgency in southeast Turkey, home to most of the country's 15 million Kurds.
Fighting flared anew in July 2015 after a two-year ceasefire collapsed, and hundreds of rebels, security forces and civilians have died in the violence.