It was a seemingly normal Saturday for Julia Martell, who was browsing the aisles of her local Walmart with a friend when she heard people screaming.

Dramatic video shows a heroic Walmart shopper armed with a gun confronting a knife-wielding maniac moments after he allegedly stabbed 11 people inside the Michigan store on Saturday night.

Authorities in Michigan say a man entered a Walmart in Traverse City on Saturday afternoon armed with a folding knife and stabbed 11 people before being stopped by shoppers and a sheriff's deputy. The attack began unfolding at 4:43 p.m., the Grand Traverse Sheriff's Office said in a statement posted online.

At least 11 people were injured in a stabbing at a Walmart in Traverse City, Michigan, officials said. The man was captured in three minutes thanks to “citizen involvement,” according to the county sheriff.

A stabbing suspect, who is believed to have acted alone, is in custody, but no motive is known, police say.