At least four players from Argentine club Arsenal were detained for interrogation after a confrontation with Brazilian police at a Copa Libertadores match on Wednesday.
Police said at least two officers and a journalist sustained minor injuries in the brawl after Atletico Mineiro's 5-2 win over the Argentine club in the city of Belo Horizonte.
Authorities said the players will likely be charged after throwing punches and kicking the officers who were trying to protect the referees as the final whistle blew at the Independencia Stadium.
Television images showed some of the players - who were not immediately identified - attacking the officers, who used shields and batons to protect themselves.
Some officers also had shotguns loaded with rubber bullets, although local police official Claudia Romualdo said no shots were fired at players. Police also were prepared to use tear gas to control the situation but it also wasn't needed.
The altercation began after several Arsenal players approached the officiating crew following the match to complain. Some police officers immediately arrived, shoving the players away and upsetting the Argentines.
The confrontation continued as police tried to escort the players from the field.
"The officers were positioned to provide safety to the visiting players so they could go into the locker rooms, but inexplicably they attacked the officers again as they left the field,'' Romualdo said.
She said one of the players hit her with a kick to her chest.
"What happened here is deplorable,'' Romualdo said.
"This is not about sports. When our law is broken, obviously we need to take action.''
Every Arsenal player and the entire Argentine delegation was kept from leaving the stadium until authorities were able to identify those who attacked the officers.
Atletico Mineiro club director Eduardo Maluf told local media that Arsenal's locker room was damaged by the Argentine delegation. He said the club will eventually ask Arsenal to pay for Atletico's losses.
"They came here to fight,'' Atletico Mineiro coach Cuca said.
"I was tired of seeing their defensive midfielders kicking (our players) away from the ball.''
Ronaldinho scored two of the goals for Atletico Mineiro, who have won all of their five matches to lead Group 3 of the Latin American club competition.
Arsenal are third in the group. Only two teams will advance to the next round.