A man lost his hand in a confrontation between fan groups during a match between Rio de Janeiro Serie B clubs Olario and America on Wednesday.
The fan's right hand was injured while attacking another supporter, the head of Rio stadium security, Joao Fiorentini, told Globo on Thursday night.
"The guy only lost his hand because he was attacking another holding a firecracker. If he hadn't attacked, none of this would've happened," said Fiorentini of the incident.
The brawl, which resulted in two injuries, was said to be between fan group members with no relation to the two clubs on the field.
According to Fiorentini, lower-level league games have become a target for more violent factions of top clubs' fan groups.
"From what we've followed on social networks, the fan who lost his hand could be a member of a Vasco da Gama [Rio's second largest club] fan club, but we're not entirely certain," he said.
"That's the problem with the less-relevant clubs," he continued. "There's been a migration of fan club members from the big teams to Serie B and C. They end up using these lesser games as a venue to stage their fights."