Walt Disney World is regularly referred to as the happiest place on earth. Well, that wasn’t the case this weekend as Austin Wuennenberg, a 21-year-old monorail operator, was killed when his monorail collided with another.

The accident happened at 2 a.m. Sunday at the Magic Kingdom section of the Florida resort. No details were released other than that Mr. Wuennenberg was killed at the scene and the other operator was fine. Five or six, depending on reports, guests were also treated at the scene.

According to the Associated Press, this is the first time in the 38 year history of the monorail system that someone was fatally injured. Which makes sense, as a monorail by definition is a single track train. How or why two trains would collide with enough force to kill someone was not being discussed by Disney Vice President of Communications Michael Griffin.

“[Accidents] are extremely rare,” Griffin told the Associated Press. “The safety of our guests and cast are a top priority above all else.”

The monorail system has now been shut down pending an investigation by the Occupational Safety and Health Administration. That might take up to six months, according to latest reports.

So if you are headed to Walt Disney World resort in Florida, be sure to learn those bus routes.