MARYVILLE, Tenn. (AP) — A police officer responding to a dispute between a father and son in eastern Tennessee was shot to death after helping get the elder man to safety, authorities said Friday.

Maryville Police Officer Kenny Moats and a colleague came under fire as they were taking cover and waiting for backup after responding to a call to intervene in a domestic dispute involving a man with a gun.

They were about 70 yards from the home when the son fired from a garage, fatally striking Moats in the neck just above his bulletproof vest, the Blount County Sheriff’s Office said.

Brian Keith Stalans, 44, was arrested and charges were pending Friday. Jail records did not indicate whether Stalans has an attorney.

The shooting happened during Thursday’s second domestic disturbance call at the home. Sheriff James Berrong said officers lacked probable cause to arrest the suspect earlier in the day, despite the fact that he was under a protective order elsewhere in the state and had triggered a warning in the federal law enforcement database.

“He had an active order of protection from Sullivan County. They had flagged him to be a dangerous individual in the NCIC. That’s all I can say,” the sheriff said.

“While we would like to turn the clock back and erase this, the officers have to make decisions within the guidelines of the law,” Berrong added. “And they did that.”

The second call, in the afternoon, included more reports of violence, and the involvement of a firearm.

Berrong declined to comment on whether Stalans had the gun legally. Tennessee law requires people who have had orders of protection filed against them to turn their guns over to someone else within 48 hours.

Moats was a 32-year-old father of three young children, and a nine-year department veteran. After spending much of his time as motorcycle officer, he was assigned to a drug task force in May.

“We know this tragedy will bring our community closer together and that will be a lasting legacy of Officer Moats,” said Maryville Police Chief Tony Crisp.

Moats is Tennessee’s second law enforcement officer killed on duty this month. Special Agent De’Greaun Frazier was shot to death on Aug. 9 during an undercover drug buy for the Tennessee Bureau in Jackson.

“Words alone cannot express the bravery of these professionals or the loss to their families and the communities they served,” said U.S. Attorney Nancy Harr.