In the photo with higher resolution, when opened in new tab and enlarge, the sign “Dwight Eisenhower Executive something or other (building?)” is visible. Is that the building directly behind the cops/shooter? Is it usual that SS would be prowling around that area? How far is this from the actual White House perimeter?
From Wikipedia:
The Eisenhower Executive Office Building (EEOB)—formerly known as the Old Executive Office Building (OEOB) and even earlier as the State, War, and Navy Building—is a U.S. government building situated just west of the White House in the U.S. capital of Washington, D.C. ~~snip~~
Located on 17th Street NW, between Pennsylvania Avenue and State Place, and West Executive Drive, the building was commissioned by President Ulysses S. Grant. It was built between 1871 and 1888, on the site of the original 1800 War/State/Navy Building[3] and the White House stables....
~~snip~~
~~~~~~~~~~~~~~~~~~~
So I would say pretty dang close to the WH.
When you see it it person, it is quite amazing to see how close a lot of buildings are to the WH.