MPD information, we believe the case has already been closed, implying the gunman has been found.
The area was closed for about three hours following the crime to pedestrian and vehicular traffic, but has since reopened.
10am UPDATE: According to the Washington Post, the victim and the shooter are one and the same:
"The fight broke out about 5:30 a.m. inside a McDonald's in the 600 block of F St. NW, police said, and may have spilled out onto the street. A police spokeswoman said one of the men had a gun and that he accidentally shot himself in the leg."