Authorities in Alamosa County say a fatal shooting last week appears to be a case of self defense.

The county sheriff’s office was called Oct. 3 to a trespassing-in-progress report in the town of Hooper. Investigators found the suspect, 53-year-old Tony Alonzo Ferrara, allegedly threatened a homeowner — Wilma Lynn Mason — with a firearm.

“In turn, Wilma, who had armed herself, apparently fired her weapon in self-defense, striking and killing Ferrara,” the county sheriff’s office said in a news release.

Sheriff Robert Jackson told The Denver Post on Thursday that Mason was housing a former girlfriend of Ferrara’s and that Ferrara — who was barred from seeing the woman by a restraining order — was trying to contact her when the shooting happened.

Ferrara’s was wielding a BB gun when he was shot, Jackson said.

“I will tell you that it looked exactly like a firearm. He was holding it and motioning it like a real firearm,” he explained.

Ferrara was pronounced dead at the scene. Jackson said he was shot by a .247-caliber, bolt-action rifle.

“After everything was done, we opted not to charge her,” Jackson said of Mason.

The Alamosa County Sheriff’s Office says it is working with the Colorado Bureau of Investigation in the case. An investigation into the shooting remains ongoing.

Hooper is 20 miles north of Alamosa in the San Luis Valley.