Surveillance video shows a gunman at an In-N-Out Burger in Idaho killing one of three victims by firing through a drive-up window, before shooting more people outside the fast-food chain restaurant.

The three people killed when a gunman opened fire at an In-N-Out Burger in Idaho have been identified as two out-of-state residents and a man from the area known for helping others get sober.

Investigators are trying to determine what led a 24-year-old man to open fire at an Idaho fast-food restaurant, in an attack that left three people dead and seven others wounded before authorities say he killed himself.