ALBUQUERQUE, N.M. –  A Native American teenager pulled from a Colorado State University tour says he and his brother were on campus for just 20 to 30 minutes when officers began questioning them. School officials say a woman in the group reported feeling nervous about their presence.

Nineteen-year-old Thomas Kanewakeron Gray says he and his 17-year-old brother were shocked when they were removed from the tour.

Gray says he believes the brothers were reported as a result of racial discrimination.

He says officers released the brothers after they provided an email on their phone showing they had reserved campus tour spots. By then, the tour had moved on without them.

The university called the case “sad and frustrating” and says it’s reviewing how similar incidents can be avoided or handled better in the future.