A positive test for explosive residue in a truck at the Wyoming Air National Guard Base in Cheyenne prompted the closure of Del Range Thursday as authorities investigated what turned out to be a harmless box, according to a spokeswoman for the Wyoming National Guard.

Diedre Forster says the alarm was raised when a truck entered the Air National Guard Base on Del Range around 11am. Forster says a routine test for explosives came up positive for explosive residue, prompting the closure of Del Range at Yellowstone Road as explosives experts ran repeated tests on a box inside the truck.  Forster says after three different tests on the box came up negative for explosives, the box was opened and found to contain a radio antennae, but no explosives.

Forster says investigators believe the positive test result may have been prompted by explosive residue on the hands of the truck driver.. Forster says at last report the driver was being questioned about the residue.