That's Texas ~ and you don't do it every time. We've got videos of even Texans calling the cops ~ actually, Texans worship the Texas Rangers ~ imagining them to be demigods just visiting the poor mortals on Earth ~ and not cops at all.
The cops in Watertown had identified a critical area. They did searches ~ not everywhere, and not everyone. Earlier that day they'd had a running gun battle with the perps who tossed a bomb.