At least 11 people have been stabbed at a Walmart in the US state of Michigan, in what the county sheriff says appears to have been a random act of violence. 

A suspect is in custody and six of the victims are in a critical condition, according to authorities in Traverse City, in the state’s north.

“Eleven is 11 too many, but thank God it wasn’t more,” Grand Traverse County Sheriff Michael Shea told reporters gathered at the scene. 

His office said in a statement that the suspect, a 42-year-old man believed to be a Michigan resident, had entered the Walmart about 4:45pm on Saturday, local time, and carried out the stabbings alone using a folding-style knife.

A sheriff’s deputy arrived on the scene within minutes and took the man into custody with the help of others in the shop, who also helped to treat the victims before more emergency services arrived, according to the sheriff’s office.

Tiffany DeFell, 36, who lives in Honor, about 40 kilometres from Traverse City, said she was in the car park 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.”

Six critical after ‘brutal act of violence’

A spokesperson for Munson Healthcare, which runs the region’s largest hospital, said 11 people were being treated for stab wounds, with six of them critical and five in a serious condition as of Saturday evening.

The ages of the victims are yet to be released.

Michigan Governor Gretchen Whitmer said she was getting updates from police about the “horrible news”.

“Our thoughts are with the victims and the community reeling from this brutal act of violence,” she said.

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

“Violence like this is unacceptable. Our thoughts are with those who were injured, and we’re thankful for the swift action of first responders,”

the statement said.

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

Traverse City is a popular vacation spot on the coast of Lake Michigan, in the state’s north.

It is known for its cherry festival, wineries and lighthouses, and is about 40 kilometres east of Sleeping Bear Dunes National Lakeshore.

AP