The powerful explosions two weeks ago startled air tower controllers and pilots flying out.
They went off in the direct path of departing flights as it turns out Fresno Police Officers nearby were setting them off.
Atop the Fresno Yosemite International Airport, controllers directing flight traffic saw what pilots called in just about the same time.
"The controllers didn't know what was going on."
Two flash type explosions in the air, catching the attention of many on the ground and much higher.
Ian Gregor, FAA Spokesman: "These flares were also spotted by the airplane pilots, one on whom said that the flares shot up higher than she was flying and she was at about 2000 feet altitude at that point."
Pilots from United Express, American Eagle and US Airways saw it. The FAA called Fresno Police to investigate. But the investigation didn't get very far.
Just feet away from the airports runway, officers at the K9 training facility were the ones sparking the concern.
Police Chief Jerry Dyer says it was part of a practice drill.
Chief Jerry Dyer: "Based on what I know at this point and time is the use of the fireworks was solely for the purposes of training to expose those animals to an environment they might find themselves in other celebrations like the Mardi Gras."
Several sources tell Action News, the fireworks were set off, but had nothing to do with any kind of training.
The Chief says the exploded fireworks were confiscated by the Fresno Fire Department.
Deputy Fire Marshall Don Macalpine says it's common for the fire department to give police fireworks to use at their discretion.
Don MacAlpine: "It can be anything from firecrackers, to anything that explodes or leaves the ground, anything that's going to be considered an illegal firework."
Dyer says he's now questioning officers who were at the training facility when the aerial devices went off to find out exactly what happened.
Chief Jerry Dyer: "It's a serious concern to me anytime that I find out that any actions or potential actions of our officers may have created any type of danger or violation of a safety rule."
Since FAA Officials don't know exactly what was set off, they don't know what immediate danger it posed to passengers, except for this.
"It's never a good thing if a pilot is distracted in flight especially during the very critical phases of flight. You just don't want a driver talking on a cell phone and you don't want a pilot worrying about a flare outside the aircraft."
I questioned four other local police agencies with K9 units to ask whether they use illegal aerial flares for training.
They all told me, they do not.
The Police Chief says he is halting the use of fireworks at the training facility for now and re-evaluating the use of them altogether.