FORT WORTH, Texas (AP) — Airlines are buying giant X-ray machines and other machinery to meet an Aug. 1 deadline to begin screening all cargo that goes on passenger planes.

Federal officials say the new rules will close a large security gap. Just four years ago, only half of all cargo was inspected.

In a sweltering warehouse next to Dallas-Fort Worth International Airport on Friday, American Airlines workers were being trained in the use of a 12-foot-high black box, an X-ray machine that was installed just two weeks ago.

Nearby, another airline employee traced a wand over boxes, looking for traces of explosives.