Investigators said James Schaffer, 20, was dressed in the costume of Vulcan, the mythical god of fire, for the California University of Pennsylvania homecoming parade and he set fire to a float that had broken down in the street once the parade was over, WTAE-TV, Pittsburgh, reported Wednesday.
Police said Schaffer was arrested and charged with arson.
A spokeswoman for the university said the student is undergoing an evaluation at a "medical facility."
"This young man is a well-known and well-liked member of the campus community. The university acknowledges the serious nature of the charges he is facing, but our immediate concern is for his health and well-being," the school said in a statement.