What a strange story...
I suppose if it really were some kind of poison gas or whatnot there'd be some human casualties as well. But it's good that such a thing raises an alert to check things out.
Birds will sometimes fly right into mirrored windows of buildings. I've never seen it, but I wonder if it is possible for a whole group of them flying together to just up and smack into a building. Flying in formation has its risks...
Curious, though.
Flying in formation has its risks...
Imagining a flock of birds comingling with the blades on rotary-wing aircraft in the dark gives new meaning to "chopper" and "pillow-fight"