Boca players Pablo Perez and Gonzalo Lamardo were treated at a hospital following the incident, which saw projectiles launched at the vehicle, smashing several windows.
On Sunday, they called the game off once again after Boca complained that a fair contest could not be guaranteed if the game was played at the River stadium.
Conmebol could instead force the second leg to be played behind closed doors or transfer the match to a neutral stadium.
The tie is now poised at 2-2, though with Boca's current stance, it's hard to see them turning up for the second leg, regardless of where it is. Sputnik spoke to Gustavo Granero, a Boca Juniors fan, about whether the game should be played and how River should be punished.
Social media is full of speculation the game will go ahead in Paraguay on December 9.
The Boca players and president, Daniel Angelici, however, insisted that they were still in no fit state to take part.
D'Onofrio said he was surprised and disappointed, claiming he and the Boca president had reached a gentleman's agreement to reschedule Saturday's game so that Boca would not have to play at a disadvantage due to players being hurt during the crowd trouble.
The CONMEBOL winners play their first match in the tournament on December 18 and could face UEFA Champions League winners Real Madrid in the final.
The postponements of what was supposed to have been a gala occasion for South American football was a huge embarrassment to CONMEBOL and Argentina, which this week hosts a summit of the Group of 20 industrialized nations.
The city of Genoa, which has historical links with River, has also offered to host the match.
The decisive leg was originally scheduled to be played on Saturday but was held back until Sunday when River Plate fans created chaotic scenes outside their Monumental stadium in Buenos Aires.
"This is a disgrace that we're talking about a situation like this, because of a few misfits, for what is a game of football", said Dominguez, reports The Independent.
"It would also be a further opportunity to give worldwide visibility in Genoa at this time of difficulty and to renew the profound sense of friendship that historically unites us with those societies".