HATTANOOGA, Tenn. — Police shot and killed an off-duty sheriff’s deputy celebrating his birthday with friends after the man drew his gun, became agitated and refused commands to drop the weapon, authorities said Wednesday.

Hamilton County Deputy Daniel Hendrix had just turned 26 on Tuesday and was celebrating with two female off-duty officers with the Chattanooga Police Department, the Tennessee Bureau of Investigation said.

“For reasons still under investigation,” the bureau’s statement said, “Hendrix appears to have changed his demeanor, became agitated, armed himself with a personal firearm, and threatened the two women, who later managed to flee the home during the exchange.”

One of the officers was able to call 911 for help around 1:30 a.m. Wednesday.

Two Chattanooga officers on duty arrived and encountered Hendrix still armed in his backyard, the TBI said.

Witnesses, the statement said, reported that Hendrix would not drop his weapon, as commanded by one of the officers. The situation “further escalated and resulted in one of the two responding officers firing his service weapon at least four times, striking Hendrix,” the release said.

Hendrix was pronounced dead at a hospital.

The deceased deputy is white. Spokespeople with the TBI and the Chattanooga Police Department declined to identify the officer who shot Hendrix or the officer’s race.

The agency continues to investigate events that led to the deputy’s death.