A Portuguese DJ is being questioned by police in Magaluf on suspicion of stabbing five Britons he reportedly mistook for a gang that attacked his brother on Halloween.

Nelson Delgado was remanded in custody after a brief court appearance over the weekend, during which he was told he would be investigated on suspicion of attempted murder in relation to the mass stabbing on the Spanish party resort. He has not yet been charged with any crime.

The initial attack took place during a Halloween party on the island of Majorca on Friday night. Early in the evening, Delgado’s brother was allegedly assaulted by a group of British men inside a nightclub while Delgado himself was working as a DJ.

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Hours later, at around 4am, a fight broke out involving up to 20 Britons – many of whom are thought to work in and around the notorious 18-30 party hotspot and are not believed to have been involved in the initial incident with Delgado’s brother.

The affray is said to have spilled outside the nightclub, where a man police believe matches Delgado’s description rampaged with a knife, stabbing five of the men.

Two of the Britons remain in a serious condition, with severe stab wounds to their backs and abdomens. The men are being treated in Majorca’s Son Espasse and Son Llatzer hospitals.

Police said they believe Delgado may have mistaken the men for the group that attacked his brother due to a mix-up over the Halloween outfits they were wearing.

Magaluf remains a popular party destination for British holidaymakers, despite a growing reputation for street violence in recent years.