Authorities have arrested one suspect and are looking for another in the deadly shooting of a southwest Missouri couple who were killed after celebrating their wedding anniversary when they interrupted a robbery at their home.

The Dallas County Sheriff's Office says in a Facebook post that Jeffrey Dale Lee Stevenson was arrested Wednesday night. He is jailed without bond in the deaths of Joe and Brandy Allen. Authorities are still searching for 22-year-old Billy Sage Medley and say he should be considered armed and dangerous.

The sheriff's office says the Allens were killed Sunday morning at their home in the town of Tunas during an apparent gunfight with the suspects. Their pickup truck was missing when authorities arrived.

The couple's 18-year-old son and 14-year-old daughter weren't home at the time.