A boy of 12 sees his best friend shot through the heart. Another of 15 is held in a cell with 150 other people and taken out every day to be burned with cigarettes.
Syria's children are perhaps the greatest victims of their country's conflict, suffering "layers and layers of emotional trauma," Save the Children's chief executive Justin Forsyth told Reuters.
Two million children, it said, face malnutrition, disease, early marriage and severe trauma, becoming innocent victims of a conflict that has already claimed 70,000 lives.
"This is a war where women and children are the biggest casualty," Forsyth told Reuters during a visit to Lebanon, where 340,000 Syrians have sought a safe haven.
Forsyth said he met a Syrian refugee boy, 12, who saw his best friend killed outside a bakery. "His friend was shot through the heart. But initially, he thought he was joking because there was no blood. They didn't realize he had been killed until they took his shirt off," he said.
The report cited new research carried out among refugee children by Bahcesehir University in Turkey, which found that one in three reported having been punched, kicked or shot at.
Children directly targeted
Two-thirds of children surveyed said that they had been separated from members of their families because of the conflict and a third said they had experienced the death of a close friend or family member.
Millions of families have fled their homes for safer ground or neighboring countries. Save the Children says 80,000 people are living in barns, parks and caves, and children struggle to find enough to eat.
Both government forces and rebels have been accused of targeting civilians and committing war crimes. Refugees say Assad's soldiers are directly targeting children.
Forsyth said he met one child who said he was in a prison cell with 150 people, including 50 children. "He was taken out every day and put in a giant wheel and burned with cigarettes. He was 15."
Save the Children says that some young boys are being used by armed groups as porters, runners and human shields, bringing them close to the front line.
Rape is being used to deliberately punish people, Forsyth said, adding that it is underreported because of the sensitivity of the issue, especially in conservative communities.
Fear of sexual violence is repeatedly cited to Save the Children as one of the main reasons for families fleeing their homes, according to the report.
It said that there are also reports of early marriage of young girls by families trying to reduce the numbers of mouths they have to feed, or hoping that a husband will be able to provide greater security from the threat of sexual violence.
Forsyth said that he met a Syrian family in Lebanon who told their 16-year-old daughter to marry an older man. "Her mother said she is beautiful and every time the (Syrian) soldiers came to the house she thought: 'They are going to rape her.'"
"Rape is being used deliberately to punish people," Forsyth said, adding that girls as young as 14 are being married off.