Actually the text at your link says this; "Two handguns without silencers were discovered at ..." Which is kind of an odd thing to say.
That is odd, but in other parts of the story it stressed that no neighbors heard anything, so they might be trying to make a point that the circumstances are odd since no one heard anything, but the guns didn't have silencers.
It also sounds like there were several empty apartments near where the shootings happened.