I don't know how true this is, but if it is (and I really doubt the Star-Telegram would print a falsehood) then it is pretty scary and screwed up:
Security details at Barack Obama's rally Wednesday stopped screening people for weapons at the front gates more than an hour before the Democratic presidential candidate took the stage at Reunion Arena.
The order to put down the metal detectors and stop checking purses and laptop bags came as a surprise to several Dallas police officers who said they believed it was a lapse in security.
Who gave the order? And why?
Update: An excellent post by Michael Froomkin on the topic here.