Flavio Augusto da Costa Leandro, 17, and Ismael Aprigio Teixeira, 18, were pronounced dead following clashes among fans in the aftermath of the Campeonato Brasileiro Serie B match between ABC and ASA in the northeastern city of Natal, reported Xinhua.
The victims, who were shot in separate incidents, were both wearing shirts of local club ABC, Folha de S. Paulo reported Saturday.
Another four ABC fans are recovering from gunshot wounds at the Santa Catarina hospital.
The incident casts renewed doubts over Brazil's ability to guarantee fans' safety during next year's FIFA World Cup.
Brazil's Superior Sports Justice Tribunal (STJD) says it has heard more than 30 cases involving violence among supporters from Brazil's top four divisions this year.
Natal's Arena das Dunas is scheduled to stage four World Cup matches next June and July.