Police in the northern Nigerian city of Kaduna have rescued more than 300 male students from an Islamic boarding school where many had been tortured and sexually abused, a police spokesperson said on Friday. Police raided a building in the Rigasa area city on Thursday where the victims including adults and minors were kept in "the most debasing and inhuman conditions in the name of teaching them the Koran and reforming them", Kaduna state police spokesperson Yakubu Sabo told AFP."We found around 100 students including children as young as nine, in chains stuffed in a small room all in the name of reforming them and making them responsible persons," Sabo said.The school which has been operating for a decade, enrolled students brought by their families to learn the Koran and be rehabilitated from drug abuse and other illnesses, police said.The proprietor of the school and six staff were arrested during the raid.Many of the rescued students bore scars on their backs and serious injuries, police said."The victims were abused. Some of them said they were sodomised by their teachers," Sabo stated.Police had been tipped off by complaints from local residents who became suspicious of what was happening inside the school.Police found a 'torture chamber'During the raid on the school, police said they found a "torture chamber" where students were chained, hung and beaten.Sabo said the victims were of different nationalities and that "two of them said during interrogation they were brought by their parents from Burkina Faso".The identities of the rescued victims were being documented to determine where they came from and to contact their families.Parents of some of the victims from within the city, contacted by police were "shocked and horrified" when they saw the condition of their children, as they had no idea what was happening inside the school.Parents were allowed to visit their children every three months, but only in select areas of the premises. "They were not allowed into the house to see what was happening... the children are only brought to them outside to meet them," Sabo said."All they thought was their children are being taught the Koran and good manners as they looked subdued," he added.Private Islamic schools are common in mainly Muslim northern Nigeria, where government services are often lacking.