Someone is marking a huge '8647' into the grounds of the National Mall in DC

A large "8647" tracing was spotted in brown grass near the WWII Memorial on the National Mall, seen from atop the Washington Monument; Park Police and the National Guard responded.
"8647" is used by opponents of Donald Trump (combining "86" = get rid of with "47" for his presidential number) and has drawn scrutiny for possibly implying violence.
It’s unclear how the markings were made and the digit "4" wasn’t clearly defined.