French police say they have arrested a woman suspected of causing a huge crash during the Tour de France by waving a sign in the riders' path on Saturday, reports BBC News.
The peloton was 45 kilometres (28 miles) from the end of the first stage, when her sign clipped German rider Tony Martin.
He fell to the ground and caused dozens of other riders to follow suit, in what was one of the Tour de France's worst ever crashes.
French authorities say the woman, who is French, is in custody in Landerneau.
Video footage of the incident has been shared widely online.
The woman can be seen holding a sign with "granny and granddad" written in German. She is looking away from the peloton coming towards her and does not see them approach, while holding her sign too far into the road.
As a result of the crash, one rider had to pull out of the Tour completely and another eight riders were treated for injuries.