BEIRUT (AP) -- Mohammed works at a Beirut supermarket where he waits on customers and carries their groceries home for a small tip that the 14-year-old saves to send later to his family in a village in northeastern Syria.
He is among hundreds of thousands of Syrian children who have dropped out of school and fled two years of conflict that have claimed the lives of more than 70,000 people.
He is also one of countless young Syrians now frequently seen wandering the streets of Beirut, pumping gas at stations and sometimes begging for money.
Aid groups warn that some 2 million children in Syria are facing, among other things, malnutrition, disease, early marriage and severe trauma as a result of the civil war.
To mark the second anniversary of the uprising against President Bashar Assad, the Britain-based charity Save the Children released a report Wednesday entitled "Childhood Under Fire." It says the conflict has left many children traumatized, unable to go to school and struggling to find enough to eat.
"I have to say I have been shocked and horrified by the stories that I've heard from the children here in Lebanon who fled from Syria," Justin Forsyth, chief executive of Save the Children, told The Associated Press at the group's offices in Beirut.
"You never want to hear a child talk about watching their friend killed or their father tortured in front of them or their brother shot through the leg," added Forsyth, who spent several days in Lebanon last week meeting children among the estimated 320,000 Syrian refugees who have fled to the neighboring country.
Syria's children will need decades to heal from the trauma, he warned.
Similarly, a report issued by UNICEF Tuesday said unrelenting violence, massive population displacement, and damage to infrastructure and essential services caused by the Syrian conflict risk leaving an entire generation of children scarred for life.
"As millions of children inside Syria and across the region witness their past and their futures disappear amidst the rubble and destruction of this prolonged conflict, the risk of them becoming a lost generation grows every day," said UNICEF Executive Director Anthony Lake.
The report said that in areas where the fighting is most intense, few people have access to fresh water. Also, one in five schools has been destroyed, damaged, or is being used to shelter displaced families.
In Aleppo, the center of months of fighting, only 6 percent of children are attending school, the report said.
At the same time, children are traumatized by seeing family members and friends killed and terrified by the sounds and scenes of conflict.
While the reports did not give a number of children killed or wounded in the civil war, the Violations Documentation Center in Syria, a key activist group that keeps tracks of Syria's dead, wounded and missing persons, says that some 5,500 children under the age of 15, including 3,800 boys and 1,700 girls, have been killed in the past two years.
VDC also says 901 boys and 28 girls are in detention while about 100 children are missing.
Forsyth said the 5,500 figure "is very conservative. A lot of children have been killed and injured."
Children in Syria were targeted early on in the uprising that began in March 2011, and rights groups routinely report on teenagers imprisoned and sometimes beaten and tortured.
One of the most shocking cases was that of Hamza al-Khatib, 13, who was from the southern village of Jiza in Daraa province, where the uprising first broke out after security forces arrested high school students who scrawled anti-regime graffiti on a wall.
Al-Khatib was arrested at an anti-government demonstration on April 29, 2011 and not seen again until his mutilated body, with his penis severed, was delivered to his family weeks later. Al-Khatib became a symbol of the revolt, driving thousands of protesters into the streets.
Countless other amateur videos have been posted by activists showing children who were killed by shooting, shelling or air raids. Some were only weeks-old.
Save the Children, which provides humanitarian relief in Syria and neighboring countries, called on all groups taking part in the conflict to allow unfettered, safe access to populations in need and to "ensure that everything is done to bring fighting to an end."
In the report, it said that young boys are being used by armed groups as porters and human shields at the front lines. It added that some girls are being married off early to protect them from a widely perceived threat of sexual violence. Both sides of the conflict in Syria have accused each other of using children to protect themselves.
"The majority of people who are raped in war are usually children and that probably is the case in Syria," said Forsyth. He added that they don't have exact numbers but "I have interviewed children who were sexually harassed."
The report says that combined with the breakdown of society in parts of the country, and more than 3 million people internally displaced, the conflict has led to "the collapse of childhood for millions of youngsters."
The number of U.N.-registered refugees topped 1 million -- half of them children -- earlier this month.
Mohammed, the Beirut supermarket employee, stopped going to school after it closed because of the fighting. As the eldest of three siblings, he was sent by his family to Beirut to stay with his maternal uncle, hoping he could find work to help sustain the family.
"I make about 15,000 pounds ($10) a day," said the portly boy from the northeastern village of Shadadeh in Hassakeh province, which witnessed heavy clashes last month forcing thousands of its residents to flee.
"If I don't send money to my family, they won't be able to buy anything," he said. Mohammed gave only his first name, fearing for his security.
At a Beirut gas station, Suleiman, a teenager wearing a T-shirt and a blue baseball cap, spends his day washing cars.
"The fighting and shelling were terrifying in my city," said the boy from the oil-rich eastern city of Deir el-Zour near the border with Iraq -- an area that sees almost daily fighting between troops and rebels.
Forsyth said even though children are by nature resilient, the trauma they have been through will have a long-term impact on their lives.
"For millions of Syrian children, the innocence of childhood has been replaced by the cruel realities of trying to survive this vicious war."
Bassem Mroue can be reached at www.twitter.com/bmroue