The suspect in a mass shooting that wounded four people in the US capital on Friday was found dead in an apartment filled with assault-type rifles, at least one pistol and a large quantity of ammunition, Washington police said.
The afternoon attack took place in a busy residential neighbourhood of northwest Washington that includes two university campuses, two private schools, apartment houses, restaurants and a subway station.
The schools went into lockdown and police advised residents to stay indoors as a manhunt stretched into the night.
Helicopters circled the area for hours following the shooting and police sirens could be heard wailing until just before 10pm local time.
The DC Police Department said the suspect was found dead in an apartment in the same area where the shooting took place.
Police photos on Twitter showed what appeared to be high-capacity magazines, a rifle tripod and three assault rifles with powerful scopes. Another picture showed a pistol.
According to NBC Washington, Police Chief Robert Contee said the suspect was thought to have killed himself as "officers were entering or breaching the apartment where the suspect was located".
Authorities earlier said a 54-year-old man, a 12-year-old girl and a woman in her 30s were hospitalised in the shooting and were in stable condition.
Assistant Police Chief Stuart Emerman later said a fourth victim, a woman in her 60s who suffered a graze wound, had come forward.
Footage posted on social media captured what sounded like a sustained burst of semi-automatic gunfire.
Asst Chief Emerman said investigators had identified Spencer through social media postings.
Police did not specify the nature of those postings.
A person identifying himself as Raymond Spencer had posted a series of messages in the online platform 4Chan with video that appeared to show gunshots fired from the vantage point of an upper-floor window, with the misspelled label: "Shool shooting!"
Police were seen pointing weapons upward at an apartment building as they escorted civilians from the scene, while several ambulances remained present for hours after the shooting began.
The University of the District of Columbia, across the street from the location of the shooting, said they were on lockdown.
"Law enforcement is on the scene. Take shelter and stay in place until further notice."
The shootings come as multiple US cities grapple with heightened anxieties about rising crime and violence.
Earlier this month, residents and commuters in New York City were rocked by a chaotic rush-hour shooting on a subway train in Brooklyn.
And in March, police arrested a suspect in a string of shootings of homeless men in Washington and New York.
The deadliest mass shooting in US history took place in Las Vegas in 2017 when a gunman killed 59 people and injured hundreds more by spraying a crowd with gunfire at a music festival.
- Agencies contributed to this report.
