Yellowstone National Park rangers have not been able to contact or locate a group of Canadian men accused of walking onto a sensitive hot spring.

On Monday, the Wyoming U.S. Attorney’s Office filed formal charges against three men who left a designated walkway at Grand Prismatic Springs. They took photos and videos of themselves and posted them on their Facebook page.

Charles Ryker Gamble, Alexey Andriyovych Lyakh and Justis Cooper Price-Brown, who have a British Columbia-based clothing business called “High on Life,” were charged with violating a regulation that requires people to stay on designated board walks or trails, and with creating or maintaining “a hazardous or physically offensive condition,” according to the criminal complaint.

Warrants were issued for their arrests.

Now they can't be found.

Yellowstone spokeswoman Charissa Reid says it's possible they have returned to Canada.

The group posted an apology on its website and social networks, expressing regret for their actions and offering to donate up to $5,000 to the park.

Messages to the group seeking comment have not been answered.

A spokesman for the U.S. Attorney's Office in Wyoming was not available Wednesday.