A 15-year-old boy was killed and a police officer was among 3 other people who were injured when someone opened fire in a crowd after an unpermitted music gathering Sunday night in Washington, D.C., authorities said.

The 3 surviving victims, including a Metropolitan Police Department officer, were stabilized at medical facilities, officials said at an evening news conference. The officer was shot in a leg, Chief Robert J. Contee III said.

The attack was the work of one person, not in custody, who opened fire as police were clearly in the area, Contee said. He did not indicate that the officer was specifically targeted, noting only that it the street was crowded.