A gunman armed with an automatic rifle is dead after opening fire inside an International House of Pancakes (IHOP) in Carson City, Nev., killing three people -- including two National Guardsmen in uniform -- and wounding six others.

Police said the unidentified shooter shot himself in the head after the rampage. He acted alone, officials said.

The Associated Press has reported that the gunman later succumbed to his injury at a Reno hospital.

Police haven't disclosed what was the motive for the shooting.

Witnesses have told the media that around 9 a.m., the gunman showed up in a blue minivan around and shot a man on a motorcycle. He then walked inside the restaurant and started shooting. The gunman then walked back outside and fired shots toward a barbecue restaurant and an H&R Block in the strip mall, and toward a casino across the street, according to The AP.

Ralph Swagler, who owns a Locals Barbecue in the strip mall, told the Reno Gazette-Journal that he saw the man pull up outside the IHOP in a blue minivan, carrying the rifle.

Carson City Sheriff's spokesman Commander Jack Freer told that officers who responded to reports of a man with a gun at the restaurant arrived to find victims shot in the parking lot. He added that more victims were found inside the restaurant.

The suspect was found down with a self-inflicted gunshot wound, Freer said.