ALBERTVILLE, Ala. (AP) — Detectives are interviewing and re-interviewing people who might hold the keys to knowing why a gunman opened fire on his co-workers at an Alabama fire hydrant factory. But a police official says the answer might prove to be elusive.

Authorities said 34-year-old Andreas Horton fatally shot two co-workers at the Mueller Co. plant in Albertville and wounded two others before dawn Tuesday before killing himself. Albertville Assistant Police Chief J.T. Cartee said that based on his experience – and the fact that Horton is dead – people might never know why it happened but that detectives are trying hard to find out.