The valedictorian of an Oklahoma City high school went missing while hiking with his family in Ecuador, according to relatives.

August Reiger, 18, has reportedly been missing in Ecuador since Sunday, his father, Chris Reiger, told Oklahoma City’s Fox 25. The Reiger family was hiking on a mountain in Banos, Ecuador, when August reportedly walked ahead of the group and disappeared.

Ecuadorian authorities quickly arrived on the scene, with more than 150 police officers and volunteers assisting in the search for Reiger, Fox News reports. However, the search failed to yield any sign of Reiger, who graduated as valedictorian of Oklahoma City’s Classen School of Advanced Studies last month.

"Unbelievable, he was (only) a few minutes ahead of us on the trail," Chris Reiger told Fox 25 from a hotel in Ecuador. “They’ve found nothing so far.”

Police have yet to discover any evidence of Reiger’s whereabouts. However, authorities believe that the valedictorian was either kidnapped or fell while hiking. “Nobody is asking for a ransom or something like that,” Chris Reiger added. “Everybody is both shocked and baffled, because they say nothing like this has happened in this town.”

In an interview with The Oklahoman, Chris Reiger noted that it seems unlikely that August would have gotten lost, adding that the entire hiking trail is visible from the family’s hotel. He also mentioned his missing son is fluent in Spanish and possesses a strong interested in anthropology, which led the family to visit Ecuador in the first place.

According to classmate Brodie Lockett, August Reiger is a talented student who has already determined his post-graduation plan before going missing. “He has got a full ride to OU, he’s got a full life waiting for him in OKC,” Lockett told Fox 25. “He was top of his class in everything.”

While information on Reiger’s disappearance is scant, his family hasn’t given up hope. According to Fox 25, Chris Reiger will be putting up missing persons posters throughout the area, and will not leave Ecuador until he discovers August’s whereabouts. “He didn’t have anything with him, no money, no water,” Reiger told Fox 25.