The man was identified as Taquan Pinkney of Southeast Washington. No arrests have been made, and police have not disclosed a motive.
Another person was fatally stabbed in Northwest Washington along 16th Street, police said.
The stabbing was reported to police around 9:24 p.m. Sunday in the 3100 block of 16th Street NW at the Sarbin Towers apartment building. The victim was later identified as 37-year-old Israel Gomez of Northwest, D.C. Police say an argument preceded the stabbing.
Police on Sunday arrested 44-year-old Policarpo Casarrubias-Rodriguez, of Northwest D.C., in connection to the incident. Casarrubias-Rodriguez was charged with first degree murder while armed.
The deaths come as the D.C. region has seen more than 180 homicides this year, according to a tracking done by The Washington Post. Of those, more than 100 have been in the District, including 58 in Southeast Washington.