This just in from the Dallas Police Department (the all-caps are the department's):

AN ON-SITE BOMB-SNIFFING DOG HIT ON A FED-EX PACKAGE IN THE BASEMENT OF ONE MAIN PLACE LOCATED AT 1201 MAIN ST. THE AREA IS BEING BLOCKED OFF AND THE BUILDING IS CURRENTLY BEING EVACUATED. EXPLOSIVE ORDINANCE SQUAD IS IN ROUTE TO THE LOCATION.

Patrick Michels was already headed to City Hall. He's swinging by now. Expect an update shortly.

Update at 10:45 a.m.: Patrick reports: Dallas Fire-Rescue spokesman Jason Evans will address media "in a sec" with more details. But, at the moment, nothing much is happening: "Lots of standing around," Patrick writes. "Paramedics snapping cell phone shots of the scene, TV guys shooting B roll, Pegasus Plaza full of evacuees standing around. It's like the first hour of a middle school dance. Cops on one side, press on the other."

Update at 11:07 a.m.: And just like that, it's over. "Chief says all clear," reports back Patrick. DFR spokesman Joel Lavender is addressing the media at this very moment. Turns out, reports Patrick, "nothing was in the box. Two sniffing dogs hit on the box, but it just contained paper files." Said Lavender, "I know it's not the most glamorous thing to find, but in a situation like this, we're just glad it's safe after all." The lieutenant also noted that the building may want to look into the company that provided and trained the dogs.