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A dog owner said an off-duty ATF agent fatally shot his mastiff puppy outside of a middle school in Spotsylvania County.

Vance Gibbs said he brings his dogs to a large field at Ni River Middle School several times a week. However, he is now traumatized after he watched his 8-month-old Presa Canario mastiff puppy Ari die in his arms.

Gibbs said it happened when he and his four puppies and three adult mastiffs were enjoying some exercise on the field Tuesday night. A golden retriever off a leash ran up to them while his dogs, which were on leashes but running free, chased after it.

The dogs then started fighting and Gibbs said he threw himself into the middle trying to get his dogs away. Meanwhile, he said the owner of the golden retriever pulled out a gun and fired twice into the ground, and then a third time hitting Ari in the side. She died minutes later.

"If he would have gave me the time in the first place, I would have got them all together," said Gibbs. "If the shots didn't scare them the one time - stop. What are you doing? Shooting a puppy? I understand he is protecting his family and everything else, but I am on the ground with your dog.

"They were fighting, going back and forth, however you want to call it. His dog approached first and escalated the whole scene. I am not saying I was right for not having my dogs on a leash in that area. Maybe that was not the best place, but there are other ways to deescalate the situation before pulling out your service weapon and shooting on school property, firing at the ground at my head in that area as I am on the floor. All that bullet has to do is ricochet and go the wrong way."

Gibbs said what makes matters worse is he believes this off-duty federal ATF agent is the same man who pulled a gun on his dogs at this park several months ago.

"I should have maybe reported it or said something, but I didn't because I just said maybe that was a freak situation and I just got out okay," he said. "If you don't have enough courage or strength to figure out other situations and can't think fast on your feet in order to make the proper decision with a firearm, you should not have one. You don't make those kinds of quick drastic decisions pulling your firearms out. That is the problem we have been having."

"The Spotsylvania Sheriff's Office is currently investigating the fatal shooting of a K9 that occurred at Ni River Middle School involving an off duty Federal ATF agent," the Spotsylvania Sheriff's Office said in a statement. "This is an ongoing investigation pending necropsy results from a lab in Warrenton, VA. The investigation will then be forwarded to the Commonwealth's Attorney for review."

FOX 5 reached out to ATF about the incident, but has not heard back from them as of Wednesday night.