A 15-year-old was killed and three people, including a police officer, were wounded during a Juneteenth event held in Washington, D.C., USA Today reports.

Washington, D.C. Metropolitan Police Chief Robert Contee said on Sunday that hundreds of people gathered for the Juneteenth advocacy and music festival called “Moechella,” continuously describing the event as an “unpermitted event.”

“We certainly want to make sure people are held accountable when they hold unpermitted events in our city,” Contee said Sunday night. “This is one of the reasons why.”

On Moechella’s Instagram page, the Juneteenth event was described as a “peaceful demonstration” with artists performing on U Street, a predominantly Black neighborhood in the D.C. area.

According to the report, the authorities attempted to break up the event after an altercation took place when another incident led to numerous people being trampled and injured in the crowd. A firearm was recovered after a second incident and shots were fired among the crowd.

The organizers of Moechella released a statement on the DMV's festival's IG page offering their condolecences to the victims as well as reaffirming the peaceful objective of their event.

Muriel Bowser, Mayor of D.C., called for accountability during a Sunday evening's press conference.

"We have a child who was killed today at an event that did not have any proper planning," Bowser said.

"We need some accountability here."