An armed bystander was seen on video heroically stopping a knife-wielding man who authorities say stabbed 11 people at a Walmart in Michigan on Saturday. The man, identified by family as Derrick Perry, is seen in the video pointing a firearm at the suspect in the store’s parking lot in Traverse City as he and other bystanders shout "drop the knife!" Perry is a Marine veteran, the New York Post reported, citing his family. "What they did was amazing," Grand Traverse County Sheriff Michael Shea told reporters during a media briefing on Sunday. Perry and the other bystanders ended the...