Three people were killed and seven others were wounded after a gunman opened fire at an In-N-Out restaurant in Twin Falls, Idaho, on Saturday before turning the gun on himself, local authorities said.

A relative confirmed to CBS News that Christopher Claunch, 59, was killed in the shooting. The president of In-N-Out also said one of their employees was among the dead but didn’t identify them.

Twin Falls Police Chief Matthew Hicks said Sunday the shooter died from a self-inflicted gunshot wound, identifying him as 24-year-old Chad Williams. Hicks said police are working to determine Williams’ motivations that led to the shooting and that his family is cooperating with law enforcement. 

“Their hearts are also broken,” he added.

The College of Southern Idaho confirmed to CBS News that Williams was a student there from August 2022 to December 2023 and that he “did not graduate with a credential,” also saying in a statement that it will cooperate with law enforcement.

Investigators said they are confident the suspect acted alone.

The situation unfolded before 2:30 p.m. local time. Social media video obtained by CBS News shows people fleeing a shopping center parking lot as multiple gunshots are heard. In the video, a person carrying what appeared to be a firearm could be seen outside the restaurant opening the doors to a parked sedan.

“First responders faced what was described as one of the most chaotic instances a law enforcement officer can face in their career,” Hicks told reporters on Sunday.

The police chief said an off-duty police officer and a civilian engaged Williams and returned gunfire.

“We believe their actions drove the suspect from the scene, preventing further casualties,” Hicks said.

Jordan Salinas, a 35-year-old from Kimberly, Idaho, was the private citizen who returned fire at the gunman, the Idaho Statesman reported.

“He did not like it when bullets started firing both ways,” Salinas told the paper Sunday morning. He posted a message on Facebook thanking the public for their support and promising to share more of his story when he is able.

Marcus James told CBS News his son, Austin, also ran toward danger to try to confront the gunman, but “intentionally did not draw his firearm” because he didn’t want law enforcement to mistake him for the attacker. He said Austin was shot and critically wounded when he “came face-to-face” with the shooter. 

Marcus said Austin’s wife and a friend, both emergency room nurses, treated Austin at the scene before he was rushed to a hospital.

Braxton Stuebe, who was working at a Dick’s Sporting Goods store near the scene, told CBS affiliate KMVT that he too came face-to-face with the gunman.

“A storm of people come in, like five, 10 people come in and specifically this lady, she was yelling, ‘There’s an active shooter, there’s an active shooter,’ running through the store, letting everybody know,” Stuebe said. He said he and a co-worker ran out the back door, and that’s when he saw the gunman.

“I saw the gun and I kind of just froze. I put my hands up and that’s when he pointed the gun directly at me,” he recalled. “The only thing I was really thinking was, don’t try and make any sudden movements, don’t try and run. Just hopefully talk to him and hopefully he can change his mind.”

“I said, I have a family. I said, you don’t have to do this. I’ll tell you whatever you want. I’ll do anything,” and then, Steube said, the gunman “just got like emotional, it seemed like. And he said to me, just get away from me, man.” But a moment later, “He turns back around and kind of has a firearm on his hip. As he’s walking backwards, he fires a shot towards me. Thankfully he had missed me.”

Two of the people injured were treated and released at St. Luke’s Magic Valley Medical Center, according to the police chief. Two people remain in critical condition, and three others are considered to be in stable condition. Hicks warned that these numbers are “preliminary” and may be updated.

In-N-Out President Lynsi Snyder said in a statement that a female employee was among the dead. Snyder did not identify the employee, but said she was “taking care of our most important asset — our Customers” at the time of the shooting. Snyder said her heart goes out to those affected by the shooting, including witnesses to the “traumatic event.” 

“We will stand together, and we will do everything we can to learn from this situation,” she wrote. 

Twin Falls resident Haley Dodaro, 43, and her mother were at In-N-Out for lunch Saturday afternoon. She told The Associated Press that while waiting in the drive-thru line, they saw people running across the road and workers bolting out of the restaurant. At first, Dodaro thought there might have been a fire, but then a man directing traffic in a reflective vest said there was a shooter.

“So that’s when we knew there was a shooting. People were running out crying and screaming. It was very scary,” Dodaro said in a text message to The AP.  

An FBI spokesperson told CBS News that its agents were on scene and assisting with the investigation. 

Twin Falls is located in southern Idaho, about 120 miles southeast of Boise.