A teenager was killed and 20 others, including an off-duty police officer, were injured after at least three shooters opened fire during a large gathering in United States capital Washington DC on Sunday, Reuters reported.

At a press conference, the state’s police chief Peter Newsham and Washington Mayor Muriel Bowser said the gathering was attended by hundreds of people and that three shooters opened fire when a dispute broke out.

Bowser added that it violated the city’s coronavirus-induced restrictions on large public meetings of over 50 people. “Sadly, several people who have no regard for human life opened fire at what had been people gathered together, enjoying themselves,” Bowser said.

Newsham said an off-duty police officer was “struggling for her life” at a local hospital, adding that she was among at least 11 injured women. The condition of others injured was not life-threatening, he said.

The deceased was identified as Christopher Brown. “I really don’t understand how my child’s life is just gone,” his mother Artecka Brown told Reuters.

The police chief said multiple weapons, including handguns, were recovered from the scene. The motive for the shooting is not clear yet.