Reuters could not immediately reach police to confirm the reports.
Local TV station FOX-5 reported, citing police, that six people were shot in the incident.
ABC affiliate WJLA-TV posted images on Twitter of ambulances carrying victims from the scene and said that there had been a "massive" police response at the intersection of 14th and Columbia streets north of the city's downtown.
(Reporting by Dan Whitcomb; Editing by Muralikumar Anantharaman and Christian Schmollinger)