Kurdish militants attacked on Monday a police convoy in southeastern Turkey which led to the killing of three police officers, security officials said.

Militants placed explosives on a highway in Mardin province and detonated them remotely as the convoy carrying police personnel passed at 1:20 pm (1020 GMT), they said. The officers were travelling in an armored vehicle.

The officials said that fighters of the outlawed Kurdistan Workers Party (PKK) were responsible for the attack.

Turkey’s mainly Kurdish southeast has been wracked by violence over the past year after a two-year ceasefire between the PKK and the state collapsed last July.

The PKK took up arms in 1984, and more than 40,000 people, mainly Kurds, have died in the ensuing violence.

Turkey is on tenterhooks after a faction of the military attempted to overthrow the government on July 15. More than 240 people were killed in the violence. Turkey has declared a three-month state of emergency to restore security following the coup attempt.