Brazilian police have arrested three people after home-made bombs were detonated at Mineirao Stadium as Cruzeiro were being relegated to the second division for the first time.
More fans suspected of violence, which included breaking seats, were being sought, police in Belo Horizonte said on Monday, a day after the game. Officers were still at the stadium collecting evidence.
Police added 13 people were taken to local hospitals for injuries inside and outside the stadium after Cruzeiro lost to Palmeiras 2-0.
The match was ended early after the first home-made bomb exploded in the stands.
Cruzeiro, founded 98 years ago, needed to win in the last round of the Brazilian championship to have a chance of avoiding their first relegation.
Cruzeiro's demotion was unexpected, but the slide began in May when the poor state of the club's finances was revealed.
One of Cruzeiro's stars is striker Fred, who played for Brazil and Lyon.
Last year, the team won the Brazilian Cup and, this year, they competed in the Copa Libertadores.