Ten men are being questioned by police after allegedly plying vulnerable young girls with alcohol and drugs before carrying out abuse at sex parties.
Around 100 detectives are involved in Operation Windermere, one of the largest child sexual exploitation investigations ever carried out by the serious crime division of Greater Manchester Police (GMP).
The men, aged between 18 and 28, are from a mix of ethnicities, police said. They were held in raids on houses in Manchester and Salford, while one man was arrested in Buxton, Derbyshire.
They have all been arrested on suspicion of trafficking within the UK for the purposes of sexual exploitation. The number of girls involved in the investigation is currently 39 but not all are victims as some are being treated as witnesses at this stage.
Around half the girls, aged from 14 upwards, were in local authority care but all were classed as vulnerable, with many from broken homes and living on the edges of society. But there is a "core group" of four to six victims on which the investigation is focusing.
The girls, from Stockport, were often picked up at various places including outside shops and bus and railway stations in Manchester, police said.
They were at first befriended, given gifts and bought take-away meals as part of a grooming process, leading to the introduction of alcohol and drugs, and ending with sexual abuse, sometimes at sex parties at houses in Manchester and Salford.
The "horrific" abuse came to light after victims spoke to their carers.
Assistant Chief Constable Terry Sweeney, of GMP, said the operation was part of a series of investigations into child sexual exploitation under way by the force, following arrests made in Bury and Rochdale in recent weeks.
And he appealed for the public's help in combating sex gangs preying on vulnerable youngsters. "I think the abuse can be stopped by the community working with us and telling us what is going on," he said.