Police in the US state of Colorado have launched an investigation into a high school in a small town after it emerged at least 100 students are involved in a sexting scandal.

The students at Cañon City High School traded hundreds of nude photographs of themselves, the authorities said on Friday, the New York Times reported.

George Welsh, the superintendent of Cañon City’s school system, said students at the school had been circulating to 400 images of “over 100 different kids” on their cell phones.

The school decided to cancel a football game this weekend after authorities came to know that many football players were also involved in the scandal.

"Because we can't guarantee that every kid we put out on the field would be clean of this circumstance, we would just rather not put a team out at all," Welsh said.

On Wednesday, the school released a press statement confirming students "have engaged in behavior where they take and pass along pictures of themselves that expose private parts of their bodies or their undergarments."

The investigation began last week after an anonymous tip was sent to the school's online "Safe2Tell" system, which is a website that asks students to anonymously report “threatening behaviors or activities endangering themselves or someone they know.”

“A courageous young individual went to an adult in our school and said they were being asked to do something they were uncomfortable with,” Walsh told Yahoo News.

“Another courageous individual offered a tip on the Safe2Tell website that told us this was more than an isolated incident.”

According to the state’s law, taking, sending or sharing nude photographs is a felony offence.

Welsh said both girls and boys were collecting and trading naked pictures. "It's not a boys-exploiting-girls situation," he said. "There was equal participation in it by both genders."