Looks like he was just rustlin' up some squab. Homeland Security at its finest.
PITTSBURGH -- Police closed off most of the Golden Triangle and blocked highway exits to Downtown while they investigated reports of an armed man atop a building on Wednesday afternoon.
After about two hours of frenzied activity, police officials held a news conference on Penn Avenue to announce that the man seen by witnesses had only been firing at pigeons.
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What we had here was a man with a pellet gun that looked like a rifle, and he was shooting at pigeons," Pittsburgh Police Chief Dom Costa said. "According to a supervisor, he brings it to work sometimes."
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The building in question is used by the Pittsburgh Culinary Institute, and was home to a Horne's department store years ago.
A little more at:
http://www.thepittsburghchannel.com/print/8188403/detail.html