Police said they were called to a flat near the Plaza de la Gesta at around daybreak last Saturday after a neighbour called in to report the "blood-curdling" screams of a woman.
"I heard a woman screaming and it frightened me," one neighbour told local media. "The screams were blood-curdling, like she was being slowly murdered."
The woman, who has not been named but is said to be of South American origin, had to be hospitalized after being found in "a state of great mental anguish".
She was discharged hours later after it was confirmed that she had suffered no physical injury.
The woman was reportedly undergoing an ‘exorcism' in the presence of several other young people and led by a "shamen".
"It absolutely had nothing to do with sanctioned Catholic exorcism," Benito Gallego, dean of Oviedo Cathedral told La Opinión A Coruña.
"It may be that it was some sort of cult ritual, faith healing or voodoo, but is far removed from the exorcism practised by the Catholic Church," he said.
Sanctioned exorcisms are regularly carried out by the Catholic Church in Spain.
In July 2014, Pope Francis made exorcisms official Catholic practice, with the Vatican hailing them as "a form of charity".
There are currently around 15 priests in Spain with Church authorization to conduct exorcisms and in 2013 a specialist exorcism squad was chosen in Madrid to tackle the "unprecented rise in demonic possession"
Earlier this year a school was forced to drop classes on exorcism at a publicly funded school after public outcry.