From the District.gov via the listservs:

“New York Ave. is blocked eastbound at 1st St. NW due to auto accident w/injuries. Detour is to M St. NW. Additionally, 1st & N St. NW is closed. Accident is affecting traffic up to several blocks from incident.”

Update 2:50 p.m.: “New York Ave. is now also closed westbound from N. Capitol St. to M St. NW.”