Former Barcelona president Josep Maria Bartomeu was among those arrested on Monday following a raid at the team's office, according to ESPN.
A local police spokesperson confirmed to ESPN that authorities made multiple arrests but would not disclose the names of those involved.
Spanish radio station Cadena SER first broke the news on Monday.
Authorities reportedly arrived at Camp Nou looking for evidence related to last year's "Barcagate" scandal, where team officials were accused of hiring third-party company I3 Ventures to smear former and current players and presidential candidates on social media for criticizing the club. The group of people attacked online included Lionel Messi, Gerard Pique, former captain Xavi Hernandez and presidential candidates Victor Font and Agusti Benedito. (Benedito has since withdrawn with Font, Toni Freixa and Joan Laporta standing in Sunday's election.)
The Catalan club rescinded the contract with I3 and refuted the allegations, and an audit conducted by PricewaterhouseCoopers later cleared the team of wrongdoing.
Barcelona released a statement Monday on the raid, not naming anyone who was detained.
"Regarding the entry and search by the Catalan Police force this morning at the Camp Nou offices...FC Barcelona have offered up their full collaboration to the legal and police authorities to help make clear facts which are subject to investigation. The information and documentation requested by the judicial police force relate strictly to the facts relative to this case.
"FC Barcelona express its utmost respect for the judicial process in place and for the principle of presumed innocence for the people affected within the remit of this investigation."
The police opened an investigation into the incident in 2020 and raided the club's offices last June looking for documents related to the allegations. According to ESPN, team employees were asked to leave the building on Monday when police returned looking for more evidence.
Last October, Bartomeu and the club's board resigned amid ongoing strife at Camp Nou that was unrelated to "Barcagate." Bartomeu was singled out by Lionel Messi during the summer when he attempted to leave the club following Barcelona's 8-2 Champions League ouster at the hands of Bayern Munich.
The club is set to elect a new president on March 7, with voting starting on Monday. Carles Tusquets has been the president in an interim role since Bartomeu's resignation.