A gunman injured four people and then killed himself in an affluent neighborhood of Washington on Friday.
According to police, two adults were taken to the hospital with serious injuries and a 12-year-old girl with a minor gunshot wound.
Another victim could therefore be treated on site.
"The suspect who we believe is responsible is now dead," Washington Police Chief Robert Contee said at a news conference Friday night.
The suspected shooter took his own life when police officers broke into a fifth-floor apartment where he was staying.
The officers found several weapons in the apartment, including a sniper rifle with a tripod.
The man's motive is not yet known, but "it was evidently his intent to kill and injure members of our community," Contee added.
According to initial findings, the man had legally acquired the weapons.
Police cordoned off the Connecticut Avenue-Van Ness neighborhood, home to several schools and embassies, on Friday afternoon after gunshots rang out in the area.
In a video circulating online, a gunman fires long bursts of automatic weapons at fleeing people - apparently from the shooter's perspective.
"It looks very authentic," Contee said of the video.
However, he clarified that it still has to be forensically confirmed and it is not known whether the video was live-streamed or uploaded afterwards.
The shooting came just over a week after a gunman opened fire on a New York subway, injuring 23 people.