Unless another life is at risk, why put yourself in harms way ? Seek cover and concealment until LEO's arrive.
You never know how amped up the "active shooter" is on meth or how well armed they are compared to you.
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A far bigger concern than meth or any other drug is the fact that once somebody starts shooting, the cops are on their way and looking for a person with a gun.
If somebody can save the day, by all means. But I wouldn't go full Mogadishu unless I'm in uniform.
