Two of the billboards are currently up in Greeley, Colorado.
Matt Wells, an account executive with Lamar Advertising, says a group of local residents purchased the space.
Residents have called the ad "offensive" and "insensitive."
According to KJCT.com, Greeley resident Kerri Salazar, who is of Native American descent, says she was livid when she learned about it. She said she doesn't have a problem with the pro-gun rights message, but she's offended the Native American people were used apparently without their consent.