India, Aug. 3 -- The suspect in a shooting at an In-N-Out Burger restaurant in southern Idaho that left three people dead and seven others injured died from a self-inflicted gunshot wound.

The suspect, identified as 24-year-old Chad Williams, acted alone in Saturday's shooting in Twin Falls, Police Chief Matthew Hicks said at a news conference.

Two of the seven injured people were treated at a hospital and released, while three were in stable condition and two remained in critical condition, authorities said.

Hicks said an off-duty state trooper and an armed civilian returned fire and helped force the gunman away from the scene, potentially preventing further casualties.

"We believe their actions helped drive the suspect away from the...