Riot police fired tear gas and worked to disperse the crowd as activists hurled stones and Molotov cocktails, the BBC reported.
A Band TV cameraman sustained "terrible head injuries" when he was hit by an explosive device, a BBC correspondent tweeted from the scene outside of the bus station.
Six other people were also injured and at least 20 protesters were arrested, O Globo newspaper reported.
Protesters were successful in rolling back a fare increase after the federal government said it would help state and municipal authorities underwrite the bill.
Last week, Rio Mayor Eduardo Paes announced a 9 percent increase in fares that went into effect Friday. Bus fare rose from 2.75 reais (about $1.20) to 3 reais (about $1.30).
After marching to the transit hub, some activists jumped the gates and vandalized ticket machines, the BBC said. Rush-hour commuters were caught up in the protests inside and outside the hub.
"We won't pay three reais," demonstrators chanted.
"We want FIFA-standard hospitals too," protesters shouted, referring to standards demanded by World Cup organizers for venues when Brazil hosts the soccer tournament event in June and July.