Authorities say a small-town south Louisiana police officer called in to calm a domestic dispute was killed with his own gun, fired by a cousin.

Sunset Police Chief Luis Padilla says 51-year-old Henry Nelson was killed Wednesday, a day before he was scheduled for a month's vacation, which he planned to spend with his teenage daughter.

Also killed was 40-year-old Shameka Johnson. St. Landry Parish Sheriff Bobby Guidroz says she and her 34-year-old sister, Shurlay Johnson, had tried to protect Courtney Jolivette Riley from her husband.

Guidroz says the husband 35-year-old Harrison Lee Riley Jr., was under arrest in a hospital.

The sheriff says Shurlay Johnson was in critical condition and Courtney Riley in stable condition.