Seven men wearing heavy vests and carrying pistols loaded with blanks ran toward the sound of the shots, stopping at the end of a long hallway. As one peeked into the foyer, the "bad guy" raised the muzzle of an AR-15, took aim and squeezed the trigger.

The simulated gunfight at the church in Haslet was part of a niche industry that trains civilians to protect their churches using the techniques and equipment of law enforcement. Rather than a bullet, the rifle fired a laser that hit Stephen Hatherley's vest — triggering an electric shock the 60-year-old Navy veteran later described as a "tingle." ...