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.

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.

The suspect in a fatal shooting at a fast-food restaurant in Idaho died of a self-inflicted gunshot wound, police said.

A Twin Falls city spokesman says that three people were killed and seven more were injured, some critically, in a shooting at an In-N-Out Burger restaurant in southern Idaho on Saturday afternoon.