Not strange at all...(Media) business as usual . 
The person who reported it to the Police dispatcher may have had an anti-gun agenda or simply saw perhaps a large capacity magazine and "educated" by fake news on guns, saw it and proclaimed "An ASSAULT Rifle"! (eyes roll).
Or the Dispatcher had an agenda, or was also ignorant.
Or the "journalist" who wrote the piece had an agenda or was ignorant.

Years ago (1989), in CA, after the "Stockton Schoolyard Shooting" the Agenda was not about the Shooter- it was against "Black, Hi-capacity, ASSAULT rifles" - Regardless of the fact that ONLY a Fully automatic rifle is an "Assault Rifle", and the gun in question was a legal civilian version Semi-automatic weapon. 
As a firearms/2ed Amendment activist I called the TV News stations, after they ALL showed FULL AUTO (machine guns) destroying watermelons. After repeated calls NOTHING was changed! My FIRST introduction and realization that the mass Media are DISHONEST!  The AGENDA trumps TRUTH !