The state-run Anadolu Agency said the explosion occurred Wednesday on a highway linking the cities of Mardin and Diyarbakir in southeast Turkey, the Associated Press reported.

Two soldiers were killed in the explosion.

Turkey has declared the PKK a terrorist organization and has banned it. The militant group has been calling for an autonomous Kurdish region since 1984.

A shaky ceasefire between the PKK, and the Turkish government collapsed in July 2015. Attacks on Turkish security forces have soared ever since.