Authorities seek a motive in the mass shooting at an Idaho In-N-Out BurgerTWIN FALLS, Idaho (AP) — Investigators on Monday were trying to determine what led a 24-year-old man to open fire at an Idaho fast-food restaurant over the weekend, in an attack that left three people dead and seven others wounded before authorities say he killed himself. Police Chief Matthew Hicks said Sunday detectives are confident that the gunman, identified as Chad Williams, acted alone in the shooting Saturday at an In-N-Out Burger in Twin Falls, a southern Idaho city of about 56,000 people. An off-duty state trooper and a civilian fired on the attacker and diverted him from the restaurant, the chief said. An In-N-Out employee was among those killed, the fast-food chain’s owner, Lynsi Snyder, said in a statement. At that point, the driver who shot the video left quickly, fearing that the man might be getting more weapons.