Alarming images showed the bus being hit by objects, with Pablo Perez taken to hospital for cuts to his arm and eye.
Clarin said six players had vomited in the dressing-room after gas drifted into bus windows smashed by River fans outside the stadium.
The South American Football Federation (CONMEBOL) initially delayed the kick-off twice, before deciding to postpone.
It was supposed to be a celebration of the passion, the colour and the sounds of Argentine football, an unprecedented spectacle the whole country could share in as River Plate and Boca Juniors dispute the Copa Libertadores final for the first time in history.
Carlos Tevez believes (much like everyone else outside of CONMEBOL) are in no condition to play the final tonight. It will not be played behind closed doors, which raises the prospect of angry Boca fans making for the stadium to take their revenge.
River Plate fans, who appear to be behind the attack, are the only fans permitted to attend the game this evening due to a rule prohibiting away fans from appearing at games between the two rivals.
Boca Juniors secretary César Martucci said that as far as he was aware the tear gas that made its way inside the bus came from the police who were trying to control the fans.
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He said he would listen to their ideas, but only if they are focused on United States national security. Our intelligence agencies continue to assess all information.
Boca were saying they are in no position to play the game due to the injured parties needing medical treatment at hospital - however it looks like they have been forced to play.
River were parachuted into the quarter-finals and Boca were kicked out the competition.
Former Argentina striker Gabriel Batistuta was distressed by the scenes and said on Twitter: "Another opportunity lost in front of the whole world that observes us. I always say matches are won and lost on the pitch, but we were not in the right condition to play today". It completely surprised me.
However, it was later confirmed the game had been suspended until 5pm local time (8pm United Kingdom time) on Sunday.
All the while thousands of River supporters sat in the stands in nervous ignorance at what was going on in the bowels of the Monumental.
The game was taking place at River's Estadio Monumental, where most of the 70,000 fans with tickets were already in place when the violence occurred.
Predictably, there has been plenty of reaction to the madness in Argentina on Twitter, with ex-players, fans and pundits alike giving their opinion.