This is the first lap incident that took Alex de Angelis, Colin Edwards and Nicky Hayden out of Sunday's San Marino Grand Prix - and almost eliminated title contender Jorge Lorenzo.
The collision occurred when local star de Angelis tried to gain places during the short right-left flick between turns 1 and 2.
The Gresini Honda rider slammed into the side of Edwards' Tech 3 Yamaha at turn two - bringing them both down and clipping the back of Lorenzo's bike before Hayden was dragged off in the carnage. Randy de Puniet was forced off track.
A furious Hayden immediately made his feelings clear to de Angelis, who had become the first ever rider from San Marino to stand on the premier-class podium just one week earlier at Indianapolis, while Edwards later labelled the de Angelis move as 'dumb'.
The accident marked the first time that de Angelis and Edwards had failed to finish a race this year, and cost Edwards fifth in the world championship.
Lorenzo kept control despite the impact and went on to finish second behind Fiat Yamaha team-mate and world championship leader Valentino Rossi.
See below for more pictures of the incident, now updated to show shots from several different angles.