Growing up in New Zealand, photographer Ruth McDowall was always intrigued by Africa. After visiting Nigeria for the first time in 2008, she returned two years later to work with at-risk young people, empowering them through photography lessons."Nigeria is a fantastic country full of great people, talent and creativity, but like most countries in the world experience war, Nigeria is now going through their own," McDowall told Refinery29.She said she saw her friends and students increasingly affected by religious and ethnic violence as Boko Haram, the armed Muslim group that has aligned itself with the Islamic State group, terrorised the country. And it was increasingly targeting young people, McDowall said."Boko Haram is using young people for strategic reasons," McDowall said. "They are trying to indoctrinate young men in their ideology and turn them into fighters. The women are also used for logistics in the camp, to fetch water and cook. They are also being forced to marry insurgents. Young people can be paid to join Boko Haram, or run errands for them. If you are broke and have nothing to lose, then you will quite possibly join their insurgency."But more and more, the group has turned to kidnapping to fill its ranks. McDowall reported that more than "500 girls have been abducted since as far back as 2009" from two northeastern states alone. Many are abducted on the way to school, while working in the fields, or from their homes during attacks on their villages."They are put through psychological abuse, forced labour, forced marriage and forced to convert to Islam. They become victims of sexual violence and rape," McDowall said.But the horrible kidnappings and abuse McDowall had been seeing since 2009 made headlines around the world last year. On the 14th of April, 2014, Boko Haram kidnapped nearly 300 schoolgirls from the town of Chibok. People around the world implored Nigerian authorities to #BringBackOurGirls. But to date, only some have managed to escape or have been rescued.McDowall said that's when she decided to find these survivors — girls and boys who had escaped — and share their portraits and their stories. The result is "Malaiku" (Angels), a powerful photo essay McDowall has shared with Refinery29.McDowall writes: "I am openly embraced by three young ladies running up to me greeting me as Aunty Ruth. During five years living in northern Nigeria, I have seen many haunted faces, but these girls look different, haunted and also broken. I wanted to photograph them looking like the strong resilient survivors they are, but as they sat slumped in their chairs, I had the heart-breaking realisation that at such a young age, these beautiful young people have lost their innocence and experienced the worst of humanity. They are just a few of the many youth that have been abducted by the Islamic extremist group Boko Haram."Ahead, her powerful portraits and the stories of the young people who managed to escape. For their safety, their names have been changed. Some captions have been edited for clarity and length.Photo caption: Lydia was kidnapped by Boko Haram while riding on a public bus in 2013. She escaped but has not been reunited with her family in Cameroon.