"I'm still sitting and grappling with the weight of realizing that it was kind of a life-or-death moment," said Julia Martell, who witnessed the stabbing, which wounded 11 people.

After nearly a dozen people were stabbed at a Walmart in Traverse City, Michigan, Saturday afternoon, the quick actions of a couple of Marines and other bystanders helped stop the attacker from causing further harm.

The authorities on Sunday said that a motive for the attack, which left 11 people injured, remained unknown. Citizens, including one who was armed, helped to apprehend the suspect, officials said.