Police did not suggest a motive for Falcao's death, but media reported that there had been a history of bad blood between Falcao and another slain Salgueiro leader.
Many of the samba parades are funded by illegal lottery groups who run a game called the jogo do bicho.
The killings come a day after police entered a Rio slum and clashed with drug gangs in shootouts that killed six people, including at least four suspected gang members.
A seventh suspected drug trafficker was killed on Wednesday in the same slum, the huge Alemao complex on the north side of the city.
Luiz Inacio Lula da Silva, Brazil's president, sent about 400 members of the elite national security force to Rio on January 14 to help fight drug gangs that control the city's 600 shantytowns.
The rest of the 6,000-strong force is to arrive before July's Pan American games, an Olympic-style competition that will host athletic teams from across the continent.
More than 600,000 Brazilian and foreign tourists are expected to gather in the coming days to celebrate Carnival.
Around 30,000 police and hundreds of troopers from the National Public Security Force will patrol tourist areas