STEAMBOAT SPRINGS, Colo. (CBS4) – The search is on for the vandals who are targeting cyclists after tacks blew out the tires of a group of triathletes over the weekend.

The crime happened Sunday morning along a stretch of road outside Steamboat Springs during the biking portion of the Steamboat Triathlon, which takes place around Lake Catamount.

Race organizers said they knew something was wrong when an unusually large number of competitors wound up with flat tires.

“All the sudden I see two flats, and I’m saying, ‘There’s something is going on,’ ” Dr. Jim McCreight said.

McCreight sponsored the triathlon and competed in it, and wound up with a flat.

“The case — what it came down to, were tacks. And in this case a number of tacks,” he said.

Over the past two days a conversation has been going on on social media that indicates a trend — both competitive and recreational cyclists say they have gotten flats from tacks on a stretch of Highway 131.

“I think Highway 131 is definitely tagged,” McCreight said.

(credit: CBS)

(credit: CBS)

Race organizers say they have heard of issues in the past but have never had a problem there before. They say they swept the course before the race.

“I hope it’s not a local, in our case a Steamboat (resident). We really take pride in outdoor recreation, (we’re a) Bike Town USA,” McCreight said.

Several reports have been handed in to the Routt County Sheriff and cyclists are urging more people to report tack issues on the highway.

“Specifically tacks that are being spray-painted to look like the road surface,” McCreight said. “This has been going on for some time, this is not isolated to just Sunday. But I will also say somebody is going to get hurt.”

The triathlon was organized by Without Limits, a Boulder company. They said they are going to promote the triathlon to make it bigger and better next year.