DIYARBAKIR, Turkey — It started as a relatively quiet Sunday in Cizre, a flashpoint town in Turkey’s predominantly Kurdish southeast where a bloody security crackdown is underway against Kurdish militants holed up in urban areas. Around noon Dec. 13, however, residents were gripped by fear as the town’s teachers, most of them natives of western Turkey, received unusual text messages from the education authorities, advising them to return to their hometowns for training starting the following day. The locals saw the messages as an omen of a looming large-scale security operation. The state, they believed, was evacuating its teachers before descending on Cizre in force. They were not mistaken.

In a matter of hours, hundreds of teachers left Cizre as thousands of soldiers and police headed to the town, backed up by tanks and armored vehicles. The authorities had ordered the purging of barricades and trenches from several neighborhoods. They had been manned since the summer by armed members of the Patriotic Revolutionary Youth Movement, the youth wing of the Kurdistan Workers Party (PKK), in a bid to seize control of various urban areas across the southeast. Anticipating a lengthy around-the-clock curfew, the locals rushed to supermarkets to stock up on food.

Later that evening came the expected curfew, the second since September, when 21 civilians, including children, perished in the clashes. Gunfire and explosions rang through the town the next day, this time coupled with the sound of tank engines and fire.

Sadun Taskin, a street vendor, watched his son die in his arms in September. Ozgur, 18, was shot in the street attempting to reach his uncle’s home, which had electricity thanks to a generator. The wounded boy could not be taken to a hospital because an ambulance would not or could not enter the besieged neighborhood. When Cizre was placed under a curfew anew, Taskin was quick to take his family to the home of relatives in a nearby village, spurred by a question his young daughter asked.