Oklahoma City water department employees alerted police of a potential shooting spree after witnessing warning signs for more than a year from a co-worker.

Channel 9 KWTV-DT reports that in obtained legal documents, co-workers of 39-year-old Pedro Calderon say he was on a downhill mental spiral, and they believed he was capable of a mass shooting.

Possibly “disgruntled and unhappy” at the water department as a waterline maintenance worker, Calderon made death threats against co-workers and allegedly showed one co-worker two loaded handguns, pulling out the magazines to prove the guns were real and loaded.

After Calderon told a city employee he was going to “come into work with guns and blow people’s heads off,” police were called and recovered 100 rounds of live ammunition in his work bag.

Though Calderon is a felon with prior convictions in two other states, the city says it was aware of his history, and that it hires felons “depending on what position they’re seeking.” Two of Calderon’s convictions involve firearms possessions, one in Michigan and the other out of Compton, California.

Calderon is technically still employed with the city but is on administrative leave pending the outcome of a hearing, News 9 reports. He was arrested for an unrelated warrant and is currently out on bond.

Source: KWTV-DT