A college student’s stunt went terribly wrong in Mankato as he fell from the back bumper of a late-night bus that offers riders a safe way back to campus from downtown bars on weekends, authorities said.

Dylan T. Smyth, 21, suffered severe head injuries about 2:20 a.m. Sunday after tumbling from the back bumper of the Late Night Express bus near Warren and Pleasant streets, according to police.

Emergency personnel arrived and transported the Minnesota State University, Mankato, student to Mayo Health System, where he was in critical condition Wednesday.

According to police, witnesses and video surveillance from the area indicated that Smyth was standing on the rear bumper of the full-size bus as it left the downtown Cherry Street stop. The video shows him in the crosswalk and then standing on the back as the bus turned left. He fell moments later.

City spokeswoman Shelly Schulz said Wednesday it’s not yet known whether Smyth was trying to duck the $1 fare or was in search of a thrill.

Smyth “is really the only person who can answer that,” Schulz said, who added that riders “are encouraged to pay a fare, but nobody is refused a ride” for not paying.

The Late Night Express is provided by the city to provide a safe ride home from the many bars downtown back to campus and housing near campus. Schulz said Smyth was not tested for intoxication.

The bus service began in 2004 in response to a night of post-homecoming mayhem near campus that saw at least 2,000 people gathered near campus in what one official called “alcohol anarchy.” Some in the mob set fires, overturned vehicles and threw rocks or bottles at some of the 41 law enforcement officers called in to restore calm.

The service started as free but soon switched to the $1 fare. The bus runs from midnight to 3 a.m. during the fall and spring semesters, and only takes riders back to the campus area and not into downtown.

Schulz said there have been “very few incidents” among the more than 100,000 rides that have been given since the service began and that operators plan no changes in the wake of Smyth’s bumper-hitching.

She added that “99.99 percent of the passengers simply want a safe ride home and are very appreciative of the service.”