Seventy-four child workers as young as 4 years old — their skin broken and palms callused from months of hauling granite — were receiving food, clothes and medical care in the West African state of Benin on Thursday after being rescued from the traffickers who sold them into heavy labor.

Children told their rescuers that at least 13 of their young companions had died in the past three months — worn out by smashing and carrying rocks and sleeping, without adequate food, in the open, U.N. officials said.

"We would break the stones, and the men would come take them away in trucks," one rescued boy, thin, filthy and heavily scratched, told The Associated Press. He looked no more than 10.

Authorities blocked most access to the children by reporters, and it was not possible to get the boy's name.

Nigerian police returned the children to Benin (search) late Wednesday, ending what Nigerian federal police inspector-general Tafa Balogoun said had been more than a year of work in the granite pits.

Tiny boys in dirty T-shirts and shorts, or bare-chested, the children hung out the windows of the buses that brought them back to their home country, staring solemnly.

Health workers were treating the children Thursday at a stadium in Cotonou (search), seaside capital of the port city of Benin.

"The children must be washed, dressed and allowed to rest a little before social workers can start interviewing them to find their parents and return them to their families," a Benin official, Latoundji Lauriano, said.

The children were returned under an August accord between Presidents Mathieu Kerekou of Benin and Olusegun Obasanjo (search) of Nigeria.

The first rescue under the pact came Sept. 27, when authorities brought back 116 children who had been put to work in the granite quarries of southwest Nigeria. Three of the children died later at a camp where Nigerian authorities brought them before repatriation, Lauriano said.

On Thursday, Benin authorities crossed into Nigeria for what Lauriano said would be a six-week mission to find more children and retrieve them.

Child labor and labor-trafficking are common across West Africa, while mass operations to rescue the victims are extremely rare. An estimated 15,000 children from impoverished Benin work in Nigerian granite pits, officials said.

Poor West African children grow up helping families with heavy labor, sometimes as soon as the children can walk steadily.

Parents often turn their children over to labor-contractors, seeing it as a way for the boys and girls to feed themselves and learn trades.

The unlucky among the children wind up in places like Nigeria's granite pits, doing hard labor for traffickers who sell the boys' and girls' work cheap and pocket much of the proceeds.

Open wounds on the bodies of the children being treated Thursday, and the calluses on their hands, testified to the severity of their labor.

Health teams were giving each child new clothes and underwear, feeding them, and inoculating them against diseases.

Nigerian officials say up to 6,000 more children could be repatriated to Benin in coming months. It was not clear why not all 15,000 would be returned, or if that involved a discrepancy in numbers.