An “irresponsible” security exercise that went awry at a Paris airport Thursday reportedly caused tempers to flare.

FedEx workers at Charles de Gaulle Airport found fake explosive devices inside a package heading to Tunisia from the U.S., according to AFP. Among the faux devices were a pressure cooker filled with nuts and bolts, detonators and other similar explosive devices, said Frederic Petit who represents FedEx employees’ CGT union.

The staff warned authorities of “imminent danger” stemming from the devices, according to AFP. Officials arrived with bomb sniffing dogs and X-Ray machines to scope out the apparent danger.

A security source told the news agency the fake devices were on its way to the U.S. Embassy in Tunisia for a training exercise. The source said the delivery of these certain packages isn’t uncommon, “it’s just the first time that a package had been opened.”

Petit called the exercise “irresponsible” given the heightened terror alert in Paris from the November attacks in which 130 people were killed by terrorists in the city.