DIYARBAKIR, Turkey (Reuters) - A Turkish police officer and a soldier were killed by sniper fire and two Kurdish militants were shot dead in separate incidents in the mainly Kurdish southeast’s biggest city, security sources said on Sunday.

Two police officers were also wounded by shrapnel from a homemade explosive during operations in the district of Sur in Diyarbakir. The soldier was shot and killed on Sunday, while the police officer was hit on Saturday before succumbing to his wounds a day later, they said.

Sur has been under a round-the-clock curfew since Dec. 2 as security forces try to eject militants from the outlawed Kurdistan Workers Party (PKK) from urban centers.

The cities of Silopi and Cizre, further east near the Syrian and Iraqi borders, have also been under curfew since mid-December. The military General Staff said 135 PKK militants in Silopi, 308 in Cizre and 101 in Sur have been killed since Dec. 15. according to media reports.

The Peoples’ Democratic Party (HDP), which has Kurdish roots, said the number of civilians killed in the three areas has reached 97, according to an emailed statement. It was not possible to verify either the military’s or the HDP’s figures.

Turkey resumed strikes on the autonomy-seeking PKK after a 2-1/2 year ceasefire collapsed in July, and the southeast is seeing the worst violence in two decades. The PKK took up arms against the state in 1984, and more than 40,000 people, mainly Kurds, have died.

A court on Sunday remanded in custody two suspects in a truck-bomb attack on a police station on Thursday that killed six people, including three small children, in one of the biggest strikes since July, the prosecutor said.

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President Tayyip Erdogan has vowed to continue operations until the PKK threat is eradicated.

Operations in Cizre continued on Sunday, and the sounds of gunfire and explosions could be heard, witnesses said.

Residents tied white rags to sticks in order to evacuate their houses as armored vehicles entered their neighborhoods to remove barricades erected by the PKK, the witnesses said.

Lines formed outside of a bakery where up to 1,500 people receive daily handouts of bread, they said. Water and electricity have been cut across much of Cizre.

In Diyarbakir, masked assailants used Molotov cocktails to set on fire a middle school late on Saturday, damaging parts of the building before firefighters brought the blaze under control, security officials said.