MAIDUGURI, Nigeria — She hears the awful sounds in her dreams. They are the moans of a dying girl.

Amina is haunted by the memory. After all, she was the one who handed the girl to Boko Haram.

Amina was a teenager herself when Boko Haram, the Islamic fighters who have rampaged across northeast Nigeria, kidnapped and conscripted her. Sixteen and scared, Amina did their bidding, seizing young girls from their homes and escorting them to a camp where many were forcibly married off to fighters.

One of the terrified girls was 14. Amina grabbed her by the wrists, leading her to a waiting vehicle. Three weeks later, the girl was dead after being gang raped.

"I think about her a lot," Amina said, swallowing hard and closing her eyes.

Boko Haram has abducted many hundreds, if not thousands, of girls and boys across the region, forcing them to fight, to cook, to clean and even to bear children. To much of the world, the kidnapping of nearly 300 girls from their school dormitory in the town of Chibok three years ago was the seminal moment in the crisis, followed by another horror: children, as young as 7 or 8, being used as suicide bombers.

The Nigerian military has made recent gains, pushing into the forests where Boko Haram hides and recapturing areas once under its control. But throughout the war, in its eighth year, hundreds of thousands of people have fled to Maiduguri, the battle-weary capital where the conflict began.

It is a place where former fighters and captives like Amina blend into the urban tapestry, a place where nearly everyone has been a victim, a collaborator — or both.

A teenager selling sugar cane on the corner may have killed someone, but he isn't sure. A smiling little boy, dressed in a school uniform as he weaves between grown-ups on the sidewalk, once bore a gun for the rebels, dragging it by the muzzle because it was too heavy for him to carry. A young woman with college ambitions was raped by several fighters, then accompanied them on village raids.

For them, building a new life is anything but certain.

"Normal life of Maiduguri masks the scars that the conflict left for some children," said Patrick Rose, a spokesman for UNICEF. "These children have experienced horrific things."

Amina

On most days, Amina, now 18, can be found on the street selling detergent and broth with her mother — the only one who knows her secret.

"I feel so guilty," she said.

A year and a half ago, insurgents would come and go in Amina's hometown in the countryside. One day they decided to take her with them, shooting her older brother and tossing his body in the bush.

They took her to a Boko Haram camp, where she was shocked by the huge number of women living there, many of them pregnant or with infants. Amina was told that she would have to marry one of the fighters, but would first accompany them on operations to help kidnap other girls. If she did not do so, she would be killed.

"On my first outing with them, I abducted three," said Amina, whose last name, like those of others in this article, is being withheld out of concern for their safety.

Capturing other girls soon became a pattern for Amina. Fighters would enter a village with guns blazing, kill and kidnap men, and expect Amina and other girls to round up the young women. They were told to leave behind older villagers and anyone nursing babies.

But it is the young girl's abduction that weighs on Amina. Wailing in the back of a Boko Haram truck, the girl told Amina that she had watched fighters kill her parents.

Amina remembers the girl being terrified, screaming that she didn't want to have sex with fighters. She fainted more than once in the vehicle that drove her to the Boko Haram camp.

At the camp, fighters didn't bother the girl for about three weeks. Then one evening, Amina watched as they came for her.

"There was one room at that camp, and any woman invited into that room knew what was going to happen in there," Amina said. "While we were eating, we heard her cries, and we knew she was being raped."

One man after another entered. It lasted three days. When it was finally over, the girl couldn't walk. Soon she was dead.

Amina escaped from the camp soon after, flagging down a driver who took her to safety in Maiduguri.

"He told me his daughter had also been captured by Boko Haram," she said.

Mustapha

Mustapha Ali sells sugar cane on a busy street corner, saving up to pay for an urban-planning degree he hopes to earn one day.

Two years ago, Mustapha, now 18, was armed with an AK-47, attacking villages alongside Boko Haram fighters who told him to join them or die.

"So I pledged my loyalty to them," Mustapha said. Two of his brothers refused to join them on that day when the rebels swarmed his village, he said, and he watched as they killed them.

He was taken to a camp where weapons were distributed to captives like him, including two boys from his village who had also been forcibly recruited.

Soon, Mustapha was riding motorbikes with Boko Haram members as they raided villages and stole cattle and sheep. During one raid, a woman was dragged out of her home.

"You pagan!" Mustapha recalled fighters shouting at her before one threw her to the ground, pulled out a knife and beheaded her.

"I was there. I saw everything," he said. "I was so afraid. From that day on, I did whatever they told me to do."

The attacks he took part in were always at night, and while Mustapha fired his weapon along with the other men when entering villages, he said, it was too dark to know where his bullets landed.

"It was hard for me to tell if I killed anyone," he said.

When Nigerian soldiers fought their way into their camp, Mustapha ran. He eventually found his way to Maiduguri, where he has been reunited with his parents, who had fled there to escape the fighters. He is living with them, putting money aside from his sugar cane sales to pay for college.

"I'm struggling," he said.