Doors opened to the public at 10 a.m., and for the first hour security officers scanned each person who came in and checked their belongings in a process that kept movement of the long lines at a crawl. Then, about 11 a.m., an order came down to allow the people in without being checked.
Several Dallas police officers said it worried them that the arena was packed with people who got in without even a cursory inspection.
They spoke on condition of anonymity because, they said, the order was made by federal officials who were in charge of security at the event.
"How can you not be concerned in this day and age," said one policeman.