A gunman opened fire at a fast-food restaurant in the western US state of Idaho on Saturday, killing an as yet unknown number of people, police said, adding that the suspect was also dead.The shooting at the In-N-Out Burger restaurant "resulted in fatalities," but authorities were still working to determine the number of victims, Twin Falls Police Chief Matthew Hicks said."It was a very chaotic scene," Hicks told reporters.Twin Falls city spokesman Josh Palmer told NBC News that three people were killed and two were wounded, but it was not clear if the gunman was counted among those casualties.Video footage aired by local media showed what appeared to be a young man with a long gun outside the In-N-Out Burger.Other video posted on social media showed more than a dozen people running out of the restaurant.Twin Falls is a city of about 56,000 people in southern Idaho, about 180 miles (290 kilometers) northwest of Salt Lake City.