Nearly 3 dozen teenage girls in Southeastern Nigeria, including some who were pregnant, were rescued from a “baby factory” where the victims were forced into sex slavery to birth children sold on the black market.

About 35 teen girls, 4 of whom were pregnant, were discovered in a hotel in the state of Anembra on Monday where they were forced to have sex and give up their children for sale.

The girls who were rescued will reportedly be “rehabilitated.” It was unclear if or when the girls would be returned to their homes. The victims were expected to be immediately handed over to the local government.

Three people have been arrested but the hotel owner is reportedly on the run.

“Baby factories” are an underground operation that authorities have busted on multiple occasions throughout Nigeria. They sometimes appear as medical clinics but operate as a front for women to sell their children. Sometimes the women have their babies unknowingly taken away or are forced into sex slavery to have children.

More about this bust and background on baby factories can be found here.