An 18-year-old in Minnesota was arrested after he allegedly tossed a young boy from a waterslide platform, causing the boy to plunge 31 feet into concrete.

Local news station KMSP reports that the 18-year-old man, identified by the New York Post as Roman Adams, approached the young boy standing on the waterslide platform at Apple Valley Aquatic Center on Tuesday afternoon, then tossed him over the edge, hurling him onto the hard concrete.

Miraculously, the boy was conscious when emergency responders arrived at the scene, though he has multiple injuries, including broken bones. He underwent surgery and is now reportedly in stable condition.

Adams is reportedly mentally disabled, and confessed to police that he threw the boy off the slide in his frustration over the long lines at the waterslide. He was not previously acquainted with the unidentified boy.

Apple Valley Police Capt. Nick Francis told news station KTSP that Adams “knew what he did was wrong.”

Adams has been charged with third-degree assault and is expected to appear in court in September. It is not clear if he is currently in custody or has been released on bail.