In an ABC News exclusive, Derrick Perry recounts his confrontation and pulling his gun on the man accused of stabbing 11 people at a Michigan Walmart.

A Walmart employee was helping a customer check out when she heard a warning that someone in the store had a knife.

One of the men who authorities say helped take down a suspect who stabbed eleven people at a Walmart told NBC News about how he sprung into action. Marine veteran Matthew Kolakowski says he took off running after the suspect and rammed him with a grocery cart to prevent him from hurting more people.

Video footage from the incident shows bystanders confront the suspect after a stabbing rampage that initially left 11 people injured.

TRAVERSE CITY, MI – Police have identified the man they believe entered a Walmart and stabbed 11 people at random. Bradford James Gille, 42, is in custody and awaiting arraignment on numerous charges in connection with the mass stabbing, police said at a press conference Sunday, July 27.

"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.