Police in Washington, D.C. arrested a 15-year-old-boy after a shooting on Juneteenth that left one person dead and three others injured, including a police officer.

The shooting happened at a Moechella event on June 19, Chase Poole, 15, was pronounced dead at the scene.

Among those shot was a police officer, who did not return fire in the crowded area. The injuries to the three adults were non-life threatening.

The Metropolitan Police Department announced Thursday the arrest of a 15-year-old boy who's being charged with first-degree murder while armed. He is being held at the Juvenile Processing Center.

WASHINGTON, DC SHOOTING: TEENAGER KILLED, 3 ADULTS, INCLUDING POLICE OFFICER INJURED

At least four people are injured after a shooting on U street Washington DC (WTTG)

Video from the scene of the shooting shows officials helping those who were lying on the ground.

Police described Moechella as an "unpermitted event" that warranted heavy police monitoring to keep attendees safe.

At least four people are injured after a shooting on U street Washington DC. (WTTG)

Washington, D.C. Mayor Muriel Bowser said at a press conference after the shooting that there needs to be "accountability."

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15-year-old Chase Poole was pronounced dead at the scene. (Antionique Murray)

"We have a child that was killed at an event that didn’t have proper planning, with people with guns involved," Bowser said. "Even with police managing crowds on-site, someone used a gun and now a child is dead."

"We need some accountability here," she added.

A shooting in Washington D.C. on Sunday has left multiple people injured, including one police officer. (Credit: @SEWINNOVATIVE) (@SEWINNOVATIVE)

Police said that the incident is still under investigation.

DC police arrest 15-year-old boy in Juneteenth shooting that left another teen dead, three injured

D.C. police said that the 15-year-old was charged with first degree murder