The Phoenix Police Department has taken full responsibility for recently losing a bag containing explosives during a security test at Phoenix Sky Harbor International Airport, and acting Chief Joe Yahner vowed to conduct a full internal investigation of the incident.

Officers were conducting a training exercise with bomb-sniffing dogs on Friday about 2:30 p.m., when a training aid with explosives inside went missing. It turned up Monday on a south Phoenix roadside.

Phoenix police find explosives

Yahner said officers had placed the blue, soft-sided Igloo container, like "you might put your lunch in," in a public area of Terminal 4. Inside were the explosive devices.

The object of the exercise was to see if trained dogs could detect explosives in the container while in an authentic setting.

"We use compounds and components that will tell us if the dogs can detect a potentially dangerous package," Yahner said.

Yahner said the explosives, two half-pound tubes of a substance typically used in mining, were in an amount "appropriate to be a fair test of the dogs."

"The officers should have had their eyes on it at all times but took their eyes off the container maybe 30 seconds, and when they looked back, it was gone," Yahner said. "The container had been stolen."

Sgt. Tommy Thompson, a police spokesman, said the explosives "could not have been set off if you'd shot a gun at them (and) wouldn't go off if they were dropped. They were not a danger to the public."

When officers realized the container had been stolen, Thompson said, an exhaustive search began that continued through Friday night and into Saturday, with no success. The U.S. Transportation Security Administration also was notified.

"The TSA mandates these training exercises and knew what we were doing," Yahner said.

On Monday, a motorist driving on Lower Buckeye Road near 19th Avenue saw the Igloo container on the side of the road and recognized it from news reports. He found the tubes of explosives still inside and called police.

The bomb squad responded to inspect the items and determined that they had not been tampered with. They were subsequently removed. But Yahner said the incident is not over.

"We will investigate the theft, but there will also be an internal investigation," Yahner said. "There will be accountability based on the investigation. We want this never to happen again."