The suspect at times went off on tangents about cigarettes filled with fiberglass and seeing videos about psychotropic drugs.

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.

"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.