Grand Traverse County Sheriff Michael Shea said a motive behind the attack by Bradford Gille, 42, of Afton, Michigan, remains unclear.

Gille, who Shea said had “prior assaultive incidents as well as controlled substance violations,” said very little as he was arrested. The man is expected to be charged with one count of terrorism and 11 counts of assault with intent to murder.

Shea praised the quick response by law officers who arrived within three minutes of receiving the call about the stabbing, as well as a group of bystanders who intervened and detained Gille in the parking lot of the store in Traverse City.

The community of about 16,000 people is along Lake Michigan.

Gille entered the store at 4:10 pm and remained there for some time before the attack began, authorities said. Calls started coming in to authorities at 4:43 pm on Saturday and a sheriff’s deputy arrived at 4:46 pm.

He said the “remarkable” efforts likely prevented others from being harmed, adding a 3 and 1/2 inch (nearly 9-centimetre) cutting blade was used in the attack.

“I cannot commend everyone that was involved enough,” Shea said at a news conference.

“When you stop and look from the time of call to the time of actual custody, the individual was detained within one minute.”

On Sunday, Gille remained jailed, and his name did not appear in Michigan’s online jail records.

Messages left Sunday with phone numbers and an email listed for Gille were not immediately returned. His previous court cases did not have an attorney’s name listed in public records.

Grand Traverse County Prosecutor Noelle Moeggenberg told reporters that the terrorism charge will be brought because the attack impacted the community, rather than one individual.

“It’s something that is done not to individual people, not to those individual victims, obviously they are most affected, but it is, we believe, in some ways done to affect the entire community, to put fear in the entire community and to change how maybe we operate on a daily basis,” Moeggenberg said.

“So that is why we are looking at that terrorism charge.”

Shea said the 11 victims were both men and women, and they ranged in age from 29 to 84 and included one Walmart employee.

Munson Medical Centre Chief Medical Officer Doctor Tom Schermerhorn, speaking at Sunday’s news conference, said one patient was treated and released; two were in serious condition; and the rest are in fair condition. All were expected to survive.

Steven Carter was loading his truck in the Walmart parking lot when he saw a man with a knife stab a woman in the throat.

About five minutes later, he said, the attacker was surrounded by shoppers in the parking lot, including one who was holding a gun.

The group of five or six people kept yelling to the man to “drop the knife,” he said, and the man responded: “I don’t care, I don’t care.” He kept backing away from the crowd before someone tackled and subdued him.

“At first, it was disbelief. I thought maybe it was like a terror attack,” said Carter, who delivers customer orders from Walmart.

“And then it was fear, disbelief, shock. And that was, it was just amazing. And it all happened fast. Like he was totally subdued on the ground by the time police arrived.”

Emergency vehicles and uniformed first responders gathered in the parking lot of the shopping centre that houses several other retail stores.

Authorities also were seen interviewing employees, still wearing blue uniform vests and name tags as the investigation unfolded.

Tiffany DeFell, who lives in Honor, about 25 miles (40 kilometres) from Traverse City, said she was in the store’s parking lot when she saw chaos erupt around her.

“It was really scary. Me and my sister were just freaking out,” she said. “This is something you see out of the movies. It’s not what you expect to see where you’re living.”

Shea said the weapon involved appeared to be a folding-style knife, adding that the stabbing started near the checkout counter of the store and that his victims were “not predetermined.”

Walmart said in a statement that it would continue to work closely with law enforcement in the investigation.

It said store associates would be paid while the store remains closed and that counselling services would be made available to them.

It wasn’t known when the store would reopen.

FBI Deputy Director Dan Bongino said in a social media post that bureau officials were responding to “provide any necessary support.”