“The soldiers would come and hold me so tight,” one 13-year-old girl said in an interview. She said she had been raped about 10 times this year at a camp in Maiduguri, the city at the center of the fight against Boko Haram, before running away for her own safety.

“They were old enough to be my parents,” she said of the soldiers who raped her.

The Nigerian military has cleared parts of the countryside to hunt for Boko Haram’s hide-outs, forcing hundreds of thousands of civilians to move into huge settlements throughout northeastern Nigeria. Many other civilians have made it to the camps on their own after fleeing Boko Haram’s deadly assaults.

Most of the camps are overflowing, with new arrivals every day. Food and water are often in short supply, residents say, and health workers are battling a cholera outbreak that has killed dozens.

At night, the camps are dimly lit. Aid workers come during the day, but typically not after sunset because of wartime curfews. Security forces tightly control who goes in and out of the camps, sometimes coercing women and girls to trade sex for food.

Government officials say they need 24-hour security to protect the residents, especially since some of the camps are regular targets of suicide bombers deployed by Boko Haram.

But in one camp, called Teachers Village, some residents said the security forces had worked out a system to select their victims. Young women were called to cook for them. After the women finished, security officers insisted that they clean up, telling them to go bathe in the officers’ quarters as the men watched.