The attack took place in the Nusaybin district of Mardin province, where the army has been conducting a military operation backed by a curfew against the PKK, it said.
The army blamed the attack on the “separatist terror group”, its customary phrase for the PKK which it never mentions by name.
The Dogan news agency said the PKK opened fire with rockets on an army bomb disposal team.
Turkey has waged an offensive against the PKK after the collapse in 2015 of a two-year ceasefire declared by the group. Hundreds of members of the Turkish security forces have been killed in attacks since then.
One of the PKK’s leaders, Cemil Bayik, warned in an interview with the BBC this month the group was ready to “escalate the war” in response to Ankara’s military campaign.
The renewed conflict has also struck at the heart of the country, with two attacks that killed dozens of people in the capital Ankara claimed by Kurdish rebels.
Over 40,000 people have been killed since the PKK took up arms in 1984 demanding a homeland for Turkey’s biggest minority. Since then, the group has pared back its demands to focus on cultural rights and a measure of autonomy.