FOIX, France – Tour de France officials are asking police to investigate the presence of tacks on the route — causing around 30 riders to encounter punctures during the 14th stage.

Speaking on French TV, race director Jean-Francois Pecheux has also credited the Sky Team — whose leader, Bradley Wiggins, is in the yellow jersey — for encouraging the pack to not speed ahead or take advantage of the mishaps of the affected riders, including defending champion Cadel Evans.

Pecheux said the search for the culprit would be “difficult” because thousands of fans were on the roadside on the Mur de Peguere climb as the riders came by.