Paraguayan officials suspended a football match between Olimpia and Cerro Porteno on Sunday after several people were injured when Cerro Porteno fans clashed with police at a stadium in the capital.

Witnesses said the violence was sparked by the detonation of high-powered firecrackers that were smuggled into the section of the Defensores del Chaco Stadium allocated to Cerro Porteno supporters.

One person told a local newspaper that some fans disarmed a police officer of his riot shield and “paraded it like a trophy” in front of the crowd in Asuncion.

Police responded by firing rubber bullets and tear gas into the stands, forcing hundreds of spectators to flee onto the pitch, according to television footage of the incident, which showed smoke engulfing portions of the stands.

The match — played before a crowd of about 40,000 — was called off after 29 minutes of play, and about 100 people were detained.

“Police officers acted immediately to ensure the safety of those in attendance,” local police said in a statement.

Security forces said at least six officers were injured — with one in serious condition — and transported to a hospital. It was not immediately clear whether any fans had been injured.

David Torales, a spokesperson for the hospital, said the injured officers sustained head injuries, lacerations, including possible stab wounds, and other injuries.

Police said they were working to “identify those who instigated the conflict so that they may be sanctioned and barred from attending future sporting events.”

The Paraguayan Football Association (APF) holds that a team must forfeit a match if its supporters force the game to be suspended.

Olimpia President Rodrigo Nogues said his club will seek the three points for the match from the APF disciplinary tribunal.

Cerro Porteno President Blas Reguera, meanwhile, said Olimpia was responsible for stadium security, citing their status as the match’s organizing club.

Olimpia currently leads Paraguay’s top football division, while Cerro Porteno sits in second place.