Four people were killed and six others wounded in the US capital late Tuesday in a shooting in one of the city's poor southeast neighborhoods, US media reported.
The toll rose overnight as a fourth victim was reported dead early Wednesday; local Fox 5 news said citing police sources.
According to witness accounts, the "drive-by" shooting, one of the capital's worst bouts of gun violence in 15 years, turned a Washington street into a war zone.
A gunman was "spraying (bullets) into a crowd" gathered outside an apartment block, Police Chief Cathy Lanier was quoted as saying in the Washington Post.
"All I saw was bodies dropping," a witness told the daily. "It was like Vietnam."
Police said an AK-47 assault weapon was used in the attack, and it was thrown from a fleeing car as suspects led authorities on a chase through the city and over the Maryland state line, said Fox 5 news.
Lanier later said three people were in custody after the shooting but no charges had been filed, according to the Post report.
Five police officers were also lightly injured in the subsequent car chase.
No motive was given for the shootings.
The city was once known as the nation's murder capital, but the number of homicides have dropped in recent years.
Police recorded 143 homicides in Washington in 2009, which, according to the Washington Post, is the lowest annual total since 1966.