DIYARBAKIR, Turkey (Reuters) - Seven people, including two civilians, were killed in Turkey’s mainly Kurdish southeast, security sources said on Monday, as the death toll from operations launched by security forces last month climbs into the hundreds.

State security forces in December intensified operations against the Kurdistan Workers Party (PKK), who dug trenches and erected barricades inside towns and cities after the collapse of a ceasefire in July, reviving a 31-year conflict that has killed 40,000 people, mainly Kurds.

The PKK, which says it is fighting for autonomy for Turkey’s Kurds, took up arms in 1984. It is designated a terrorist group by Turkey, the United States and European Union.

A 35-year-old father of three was killed outside of his house in the town of Cizre, near the Iraqi and Syrian borders, amid violent clashes between the PKK and security forces, an official said on condition of anonymity.

Another man, aged 36, was shot in the head and left for dead while herding livestock outside of Cizre, he said. The sound of gunfire and explosions could be heard after nightfall in Cizre, witnesses said.

In Sirnak, two police officers were killed and three wounded when the bus they were on was hit by rocket fire, security sources said.

In the nearby town of Idil, three police officers were killed and seven wounded when a bomb ripped through an armoured vehicle on Sunday near the municipality building, sources said.

PKK fighters attacked a local military base with rocket launchers and rifles, causing no casualties, sources said. Reinforcements were sent to the town from neighbouring Cizre and clashes were continuing in the area.

In the region’s largest city Diyarbakir, PKK militants fired a rocket launcher at a police armoured vehicle but instead hit a transformer, cutting off power in the area, sources said.

Ankara launched a peace process with the PKK’s jailed leader Abdullah Ocalan in late 2012, but it ground to a halt early in 2015 ahead of a general election. Turkey’s leaders have said they will continue operations until the militants are defeated.

For much of the three-decade insurgency, fighting has remained largely in the countryside, but the latest violence has focused on urban areas. Cizre and Silopi, further east, have been under round-the-clock curfew since Dec. 14 as security forces try to root out PKK militants from urban centres.

The army says it has killed 320 militants in Cizre, 135 in Silopi and 101 in the Sur district of Diyarbakir city since operations began last month. The pro-Kurdish HDP party says some 100 civilians have been killed in these areas.

It was not immediately clear how many security forces have died since December. President Tayyip Erdogan said last week that about 300 police officers and soldiers have died since July.