During a graduation ceremony held at Walt Disney Concert Hall on Thursday evening, violence broke out inside as well as outside the concert venue, and a shooting may have occurred.

The L.A. County Probation Department said in a statement late Thursday that the department had co-hosted a graduation ceremony that evening for 100 high schoolers, including 29 detained youths.

At the end of the ceremony, a community member leaped from a second-story balcony and assaulted a graduate. All the detained youths had already left the auditorium and were in a secure holding area.

“The Probation Special Enforcement Operations unit quickly responded, containing the incident and restoring order inside the auditorium,” the statement said.

Outside, however, a brawl then broke out. Four people were detained pending further investigation, the Probation Department said.

Los Angeles police officers who responded after reports of the violence found evidence of a shooting near the concert hall, though officers did not locate anyone who was wounded.

Police responded to the 100 block of Grand Avenue shortly after 6 p.m. after reports of a group fighting and a possible shooting, LAPD Officer Kevin Terzes said.

Officers recovered shell casings in the area, he said, but found no victims. Terzes did not know where exactly the casings were found.

Grand Avenue and Hope Street were closed between 1st and 2nd streets Thursday night due to the investigation.

The Probation Department did not explain what might have prompted the assault inside or the fight outside.