LAKE BUENA VISTA, Fla. (AP) — Officials at Walt Disney World Resort were investigating what caused the first fatal accident in the 38-year history of the park's Monorail, a one-time symbol of founder Walt Disney's vision for future transportation.

One of the monorail trains crashed into another early Sunday in the park's Magic Kingdom section, killing one of the train's operators, emergency officials said.

At least five guests were treated at the scene for minor injuries, authorities said. The other train's operator was not injured, but was emotionally shaken and taken to a hospital.

The transit system, which shuttles thousands of visitors around the sprawling resort each day, was shut down while authorities investigated.

"To see the accident, to see the scene of what had happened and the fact that there was a life that was lost, it was very sad. It was very somber," said Bo Jones, deputy chief for Reedy Creek Fire Department.

Disney's senior spokesman Michael Griffin identified the driver as 21-year-old Austin Wuennenberg. Griffin would not discuss how long Wuennenberg had been with Disney or the circumstances surrounding the crash. Disney officials also declined to discuss how the monorail system operates.

"They are extremely rare," Griffin said of accidents at the park. "The safety of our guests and cast are a top priority above all else."

A spokeswoman for Stetson University in nearby DeLand confirmed that Wuennenberg was a student at the school. A woman standing in front of Wuennenberg's home in Kissimmee declined to comment Sunday afternoon and directed questions to Disney officials, saying the family wanted "private time to grieve."

One of Wuennenberg's former Stetson classmates, Brandon Ross, said the 21-year-old had scheduled his classes around his Disney job and took precautions if he was working a night shift. Ross said his friend would make the hour-long drive from DeLand to the Orlando area the day before his shift so he wouldn't be tired when he operated the train.

"He seemed to be a pretty safe person," said Ross, 22. "He's not reckless at all."

Wuennenberg studied computer science, said Ross, who sometimes asked for his help on school projects and called him smart and talented. "He was really good with computers."

A similar monorail first opened at Disneyland in Anaheim, Calif., in 1959, inspired by a futuristic train system in Germany. The larger updated version at the Florida park opened in 1971.

Catherine McKenna, 45, and her family were visiting the theme park from Ireland. The family had planned to use the monorail to travel to the Magic Kingdom last Friday but said they were told the train was broken. They took a ferry but returned on the monorail later that day.

"It's very sad," McKenna said. "You would be very afraid to use it again."

Disney spokeswoman Zoraya Suarez said the park had boosted other forms of transport — such as ferries, boats and buses — for visitors Sunday.

"Our guests are getting around fine," she said.

Seventeen-year-old Ethan Meus, visiting from Dubuque, Iowa, said he and his family took the monorail to dinner at a resort hotel Saturday night. Meus watched the Magic Kingdom fireworks from the monorail on the way back to his hotel and said he didn't notice any problems with the train.

"It's pretty shocking to hear that a driver was killed," Meus said.

"You would think it would be so safe," said 20-year-old Lauren Shoebottom, who was visiting the park from London. "You don't expect it on holiday, do you?"

Griffin issued a statement offering condolences to the employee's family and saying the monorail was closed.

"It's a bit shocking," said 22-year-old Danielle Williams, of London. "Disney seems so perfect."