Turkish Prime Minister Tayyip Erdogan described the gunning down of three members of the security forces in the southern province of Nigde on Thursday as a “nefarious terrorist attack” but did not say who was responsible.

Paramilitary and regular police officers were manning a checkpoint when the attackers opened fire from a truck, Turkey’s Dogan News Agency (DHA) said. The driver of the truck, which was stolen, was also killed in the exchange of fire.

Speaking at a rally before March 30 local elections in the northwestern town of Sakarya, Erdogan confirmed the attack.