Kurdistan Workers Party (PKK) militants detonated the explosives by remote control near a village in the Derik district of Mardin province at 3:10 pm (0810 EDT), the sources said, adding an operation was launched in the area to capture those responsible.
Suspected ISIS suicide bombers killed 41 people and injured 239 in an attack on Istanbul's main airport on Wednesday.
Conflict between the PKK and the Turkish military flared up last July after the collapse of a ceasefire.
Thousands of militants, security force members and civilians have been killed in fighting across the mainly Kurdish southeast since then.
Earlier on Wednesday, the Turkish military said two soldiers were killed and another three wounded on Tuesday evening in two attacks by PKK fighters in the southeast's Diyarbakir province.
The militants launched one attack in the Lice area of Diyarbakir, wounding four soldiers, one of whom later died in hospital, the armed forces statement said.
It said another soldier was shot dead by PKK militants in Diyarbakir's Bismil district after he got out of a vehicle in front of his house.
More than 40,000 people have been killed in the conflict since the PKK, designated a terrorist group by Turkey and its Western allies, began its insurgency in 1984. Violence has surged since the collapse of a ceasefire last July, Abna reported.
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