The band Mumford and Sons vowed never again to play a music festival in Sweden following reports of 17 sexual assaults over the weekend.

On Tuesday, members of the alternative band posted a message on their Facebook account that they were “appalled” learning of the news that numerous sexual assaults took place at the Bravalla music festival in Sweden, where they performed. (RELATED: Swedish Girl Raped As Police Prepare To Hand Out Anti-Groping Armbands)

“We’re appalled to hear what happened at the Bravalla Festival last weekend,” they wrote. “Festivals are a celebration of music and people, a place to let go and feel safe doing so. We’re gutted by these hideous reports.”

“We won’t play at this festival again until we’ve had assurances from the police and organizers that they’re doing something to combat what appears to be a disgustingly high rate of reported sexual violence,” they added.

Authorities are investigating five reports of rape and 12 others of sexual assault, according to a Variety report. The Independent reports that the perpetrators were likely recent migrants.