Arizona Sheriff Joe Arpaio has instructed his deputies to carry AR-15 assault rifles at all times following a local detention officer's shooting death on Thursday, KPHO-TV reported.

"Should any off-duty deputy come across a crime being committed, it is the policy of this office for that deputy to take the appropriate action to resolve the situation," Arpaio said at a public unveiling of the 400 firearms purchased by the Maricopa County Sheriff's Department on Friday, which officials said had been scheduled before the fatal attack on 27-year-old Jorge Vargas, who was shot and killed at his home.

According to KNXV-TV, Vargas was in his driveway working on his car when he was shot. A neighbor said she saw him bleeding from the throat when she ran to his side after he was shot. Witnesses said they saw a man running from the scene following the shooting, but no suspect has been identified.

"We don't appreciate people killing our deputy sheriffs and officers that work in the jail system," Arpaio said at a press conference Thursday. "Watch out, we're ready for battle and going to take whatever action we need."

Watch KNXV's report, aired Thursday, below.

[h/t ABC News]