Four fraternity members at San Diego State University are facing felony charges after a pledge was set on fire during a skit at a party last year, leaving him hospitalized for weeks with third-degree burns, prosecutors said Monday.

The fire happened on Feb. 17, 2024, when the Phi Kappa Psi fraternity held a large party at its house, despite being on probation, court documents show. While under probation, the fraternity was required to “demonstrate exemplary compliance with university policies,” according to the college’s guidelines.

Instead, prosecutors said, the fraternity members planned a skit during which a pledge would be set on fire.

After drinking alcohol in the presence of the fraternity president, Caden Cooper, 22, the three younger men — Christopher Serrano, 20, and Lars Larsen, 19, both pledges, and Lucas Cowling, 20 — then performed the skit, prosecutors said.

Mr. Larsen was set on fire and wounded, prosecutors said, forcing him to spend weeks in the hospital for treatment of third-degree burns covering 16 percent of his body, mostly on his legs.

The charges against Mr. Cooper, Mr. Cowling and Mr. Serrano include recklessly causing a fire with great bodily injury; conspiracy to commit an act injurious to the public; and violating the social host ordinance. If convicted of all the charges, they would face a sentence of probation up to seven years, two months in prison.

Mr. Larsen himself was charged. The San Diego County District Attorney’s office said that he, as well as Mr. Cooper and Mr. Cowling, also tried to lie to investigators in the case, deleted evidence on social media, and told other fraternity members to destroy evidence and not speak to anyone about what happened at the party.

All four men have pleaded not guilty.

Lawyers representing Mr. Cooper and Mr. Cowling did not immediately respond to messages requesting comment on Tuesday. Contact information for lawyers for Mr. Serrano and Mr. Larsen was not immediately available.

The four students were released on Monday, but the court ordered them not to participate in any fraternity parties, not to participate in any recruitment events for the fraternity, and to obey all laws, including those related to alcohol consumption.

The university said Tuesday that it would begin its own administrative investigation into the conduct of the students and the fraternity, now that the police investigation was complete.

After it confirmed the details, the dean of students office immediately put the Phi Kappa Psi chapter on interim suspension, which remains in effect, college officials confirmed on Tuesday.

Additional action was taken, but the office said it could not reveal specifics because of student privacy laws.

“The university prioritizes the health and safety of our campus community,” college officials said in a statement, “and has high expectations for how all members of the university community, including students, behave in the interest of individual and community safety and well-being.”

At least half a dozen fraternities at San Diego State University have been put on probation in the last two years, officials said.