(WASHINGTON) — Police are asking for the public’s help after a mass shooting broke out in Washington, D.C., killing a 15-year-old boy.

The Sunday night shooting took place during a festival called “Moechella,” which was celebrating Juneteenth, officials said.

The 15-year-old boy, identified by his first name Chase, was killed and three people, including a D.C. Metropolitan police officer, were injured, Metropolitan Police Chief Robert Contee said.

The officer is expected to be OK and the two civilians were listed in stable condition, officials said Sunday night.

No suspects are in custody, authorities said.

Police are collecting evidence and interviewing witnesses, Contee said in a statement Monday.

A reward up to $25,000 has been offered for information leading to the gunman’s arrest and conviction.

“The person who took Chase’s life and brought this violence to our community must be held accountable,” Contee said.

Anyone with information is urged to call the Metropolitan Police Department at 202-727-9099.

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