The cause for the riot in the visiting fans block on Friday evening was unclear, police said.
According to a police report, one fan was “severely attacked” and kicked while already on the ground. After the police intervened, the clashes between fans and police officers began. The match was interrupted for around five minutes due to the incidents but eventually resumed.
A fan organization for Hamburg’s St Pauli club called the police intervention “inappropriate and disproportionate.”
The police say they entered the brawl to prevent an escalation of violence.
Hannover 96 coach Stefan Leitl and St Pauli coach Fabian Hürzeler condemned the riots.
After the game, the police reported that St Pauli fans were attacked in the streets with bottles, rocks and pyrotechnics. The police responded by using pepper spray.