DIYARBAKIR, Turkey (Reuters) – Security forces killed 20 Kurdish militants in southeast Turkey while three Turkish soldiers died in a rebel attack, the military said on Wednesday, as authorities widened a curfew in the mainly Kurdish region’s largest city, Diyarbakir.

Hundreds of locals, including children and the elderly, fled curfew-bound areas of Diyarbakir’s Sur district as gunfire and blasts resounded and police helicopters flew overhead, a Reuters witness said. Some people cried as they carried away possessions.

The southeast has endured the worst violence in two decades since a 2-1/2-year-old ceasefire between the state and Kurdistan Workers Party (PKK) militants collapsed in July, reviving a conflict that has killed 40,000 people since 1984.

The army said 11 PKK members died in the town of Cizre, near the Syrian border, and nine more in Sur on Tuesday, bringing the militant death toll in the two towns to some 600 since security operations began there last month.

It said three soldiers were killed in a militant attack in Sur, where security sources said militants opened fire with rifles and a rocket launcher.

The ancient Sur district, enclosed by Roman city walls, has suffered extensive damage in the fighting and much of it has been under a round-the-clock curfew since Dec. 2.

The district governor’s office said the curfew was extended to five more districts so security forces could remove explosive devices and barricades and fill in ditches set up by militants.

Turkey, the United States and the European Union all classify the PKK as a terrorist organization. The PKK says it is fighting for autonomy for Turkey’s Kurdish minority.

Rights groups and locals have voiced growing concern about the civilian death toll in the security operations since last month. The pro-Kurdish HDP party puts the toll at nearly 120.

Rights groups have highlighted the plight of some 28 people sheltering in a Cizre cellar, where four have died and three are in a critical condition, according to information obtained by Emma Sinclair-Webb of Human Rights Watch.

“Medical attention is not being provided to those in need. This is an urgent situation that the Turkish government needs to address imminently to prevent loss of life,” she told a news conference in Istanbul.

In Diyarbakir, healthcare groups including a doctors’ association and union called for ambulances to be allowed to rescue the wounded in Cizre, where ongoing clashes and the curfew are preventing people from moving about.

(Additional reporting by Ayla Jean Yackley in Istanbul, Gulsen Solaker in Ankara; Writing by Daren Butler; Editing by David Dolan and Mark Heinrich)