STORY: The incident occurred in the evening at the intersection of 14th and U streets, an area crowded with bars and restaurants. It wasn't immediately clear if the suspect was in custody.
Police said the shooting took place during an "unpermitted" music festival called "Moechella". Shortly before the shooting, a firearm had been recovered from an individual in the area. Another firearm was found in the possession of one of the injured victims, police said.
"There's a theme that you see here, illegal firearms in the hands of people who should not have them make events like this unsafe for people who just want to enjoy the beautiful weather, who want to enjoy Father's Day and want to enjoy our city. This is unacceptable," Police Chief Robert J. Contee III told reporters late Sunday evening.
District of Colmbia mayor Muriel Bowser added "we have a child who was killed today at an event that did not have any proper planning for the number of people who are here in with guns involved".
The injured are in stable condition, police said, adding that they had not recovered the firearm used in the shooting.