The woman who allegedly caused a massive pileup during the first stage of the Tour de France has reportedly been found and arrested ... ending a 3-day search for the spectator.
As we previously reported, a woman stepped onto the road and held a cardboard sign towards the TV cameras as the pack of riders approached on Saturday ... and made contact with German rider Tony Martin.
The hit caused a chain reaction ... with dozens of other riders crashing behind him as a result.