About 50 students have been freed from a religious school in Karachi, Pakistan - where some were being kept in chains, local officials say.
Reports suggest the male students, some as young as 12, were kept in what amounted to a torture chamber.
They were beaten, deprived of food and pressured to join the Taliban, the reports say.
At least two people helping run the madrassa have been arrested, but the head escaped, police said.
Pakistan's interior minister has ordered an inquiry into the incident.
The captives were found during a police raid on the site in the central Sohrab Goth district of Karachi late on Monday, police said.
"Those recovered are aged between 12 and 50 and are mainly of Pashtun ethnicity," Gadap Town police superintendent Rao Anwar told Pakistan's Express Tribune newspaper.
A police official told the BBC that most of the students were drug addicts whose parents had left them at the madrassa for treatment.
One boy said Taliban members had visited the seminary and told them to "prepare for battle".
Some Islamic schools in Pakistan are accused of being training camps for militants, and a police official told AFP news agency that the possibility of such links would be part of the investigation into this school.
Government records suggest there are more than 15,000 madrassas in Pakistan, providing education for more than two million students - about 5% of Pakistani children in formal education, AFP said.
But officials suspect thousands more unregistered schools provide the only affordable education option for children of poverty-stricken families.