An IRS agent fatally shot a another agent while they were training at a Phoenix gun range

• An IRS agent was shot and killed by a fellow agent during a training exercise.
• The victim previously served 20 years with the Arizona Air National Guard.

An IRS special agent who had decades of military experience was shot and killed by a fellow IRS agent while training at a gun range last week.

Officials confirmed that the victim, 47-year-old Patrick Bauer, was accidentally shot at a federal gun range on Thursday in Phoenix, Arizona, a Federal Bureau of Prisons spokesperson told local CBS affiliate AZ Family.

Bauer was taken to a local hospital, where he died from his injuries, Charlotte M. Dennis, an IRS Criminal Investigation spokesperson, told AZ Family.

"Our concern today is for the agent and their family," Dennis told the outlet.

Bauer was also a retired master sergeant with the Arizona Air National Guard, serving with the 161st Air Refueling Wing Security Forces Squadron.

The squadron posted a tribute to Bauer on Facebook.

"On behalf of the men and women of the 161st we express our deepest condolences to the family, friends, and all those affected by the passing of IRS Special Agents and (Ret) MSgt Patrick Bauer," the statement said. "Bauer retired in 2016 after over 20 years of service with the 161st Security Forces Squadron. Your service to our state and nation will be greatly missed."

Bauer leaves behind a wife and four children.

"Our hearts go out to MSgt Bauer's family, friends and all those who had the privilege to work with him. His service to the state and nation will forever be remembered," Maj. Gen. Kerry L. Muehlenbeck, an Arizona National Guard Adjutant General, said in a statement to AZ Family.

The FBI is investigating Bauer's death and will turn over findings to the US Attorney's Office, local affiliate ABC 15 reported.

"We are experiencing the shock of all this," Lt. Col. Jeffrey Robertson, who had known Bauer for nearly a decade, told ABC. 15. "He was an incredible human, a great leader."

The tragic incident comes months after many questioned why IRS agents needed to be armed.

The agency's longstanding Criminal Investigation Division conducts potentially dangerous investigatory work and was previously responsible for bringing down mob boss Al Capone in the 1930s.