The last time there were confirmed deaths of American citizens at the hands of the national guard was the 1985 MOVE bombing in Philadelphia. The national guard assisted the city and state police in bombing the headquarters of the MOVE organization.
Again slowly, they dropped fire bombs from a state police helicopter onto a building occupied by American citizens, including children.
5 children, 2 of which were infants, and 6 adults were killed. The fire spread quickly burning down 61 buildings in the city and leaving 250 people homeless.
None of the actors in the bombing were ever charged with a crime.
40 years is far too short. Sadly we are well on the path to ending this streak.