(CBS News) -- The number of registered child refugees fleeing Syria's violence has topped the 1 million mark in another grim milestone of the deepening conflict, two U.N. agencies said Friday.
Roughly half of all the nearly 2 million registered refugees from Syria are children, and some 740,000 of those are under the age of 11, according to the U.N. refugee and children's agencies.
"This one millionth child refugee is not just another number," said Anthony Lake, the head of UNICEF, the U.N. children's agency. "This is a real child ripped from home, maybe even from a family, facing horrors we can only begin to comprehend."
The children's ordeals are not over once they escape Syria, said Antonio Guterres, the head of the Office for the U.N. High Commissioner for Refugees, known as UNHCR.
"Even after they have crossed a border to safety, they are traumatized, depressed and in need of a reason for hope," he said.
His agency said it tries to ensure that babies born in exile are provided with birth certificates, preventing them from becoming stateless, and that all refugee families and children live in some form of safe shelter.
But the threats to refugee children are rising, the agencies say, including child labor, early marriage and the potential for sexual exploitation and trafficking. More than 3,500 children in Jordan, Lebanon and Iraq have crossed Syria's borders unaccompanied or separated from their families, according to the U.N. figures.
In May, CBS News correspondent Clarissa Ward traveled to a refugee camp in Jordan where Syrian parents were selling their daughters into marriage with wealth Arab men in a desperate bid to survive.
The agencies say some 7,000 children are among the more than 100,000 killed in the unrest in Syria, which began in March 2011 and later exploded into a civil war.
Most of the refugees fleeing Syria have arrived in Lebanon, Jordan, Turkey, Iraq and Egypt. However, U.N. officials say that increasingly Syrians are fleeing to North Africa and Europe.
The two U.N. agencies estimate that more than 2 million children also have been displaced within Syria.