It's actually been a problem before . . .

We were shooting a movie behind Circa that used fake guns, with all the right permits, and plenty of calls confirming that the police, both Wayne and DPD , were aware that there would be guns involved.

Even so, they ran up on everyone, guns drawn, screaming like "we've got action", even as the speakerbox on their shoulder sceamed, "STAND DOWN! STAND DOWN! ITS A MOVIE". These cops know what they're doing. . .