They were among 38 arrested followed large-scale police raids yesterday in Berevoesti, 170 kilometres north of Bucharest, when five people including two boys aged 10 and 12 were freed.
The captives were "attached with chains and straps... beaten (and) humiliated", starved of food and fed on scraps, prosecutors from the DIICOT organised crime investigation unit said.
They were "left fully naked, cold and hot water being thrown alternatively on them. Their hands and feet were tied and they were told to eat off the ground or to fight each other to amuse the suspects," they said.
90 people from Gamacesti, a Roma district within the municipality of Berevoesti in the Arges region, were initially thought to have been involved.
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"Their treatment was terrible," said Mihaela Porime, a spokeswoman for the DIICOT. Some of the victims are believed to have suffered sexual abuse as well, prosecutors said.
Those freed yesterday "had visible traces of open wounds all over their bodies, particularly their scalps. They appeared physically and psychologically traumatised," Adrian Macovei from the DGASPC child protection agency told local media.
"These people, if they came to work in our home, we'd give them food, we gave them shelter, we didn't do anything bad to them," said one woman who refused to give her name.
"They were unhappy, with no mother or father. We felt sorry for them. They were like our children," she told AFP.
Berevoesti's mayor Florin Proca said he was "stunned".
"I couldn't imagine that in 2016 such soulless people could exist. I have seen shocking photos of the slaves, people held against their will, abused," he told AFP.