For New Englanders, one of 2008’s most horrifying stories was the accidental death of an 8-year-old at a Massachusetts gun show on Oct. 26. With his father watching, Christopher Bizilj was permitted to fire a powerful submachine gun generally reserved for military and police use. The gun recoiled, lodging a bullet in the child’s head.

It never should have happened. Pelham, Mass., Police Chief Edward Fleury, who organized and promoted the show, is reportedly distraught but ought to have known better. On Dec. 4, he was charged, appropriately, with involuntary manslaughter. Two Connecticut gun dealers who provided machine guns for the show have also been charged.

The Oct. 26 Machine Gun Shoot and Firearms Expo was hosted by the Westfield, Mass., Sportsman’s Club. Mr. Fleury advertised the event online, especially encouraging children to attend. Although Massachusetts law permits children to fire a weapon if supervised, it is illegal to give anyone under 18 a machine gun, according to District Atty. William Bennett.

Experienced gun users know that the weapon the boy fired, the Israeli-made Micro Uzi, can be quite dangerous even for adults to handle. Designed as a battlefield weapon, it can fire a few dozen rounds in 30 seconds. Its forceful recoil can challenge even a strong marksman.

As a gun-safety instructor for several years, Mr. Fleury ought to have used some common sense, and barred children from testing such powerful weapons. Christopher’s father, Dr. Charles Bizilj, presumably trusted that the show’s organizers were following proper precautions. Yet, though the advertisements promised that a certified firearms instructor would guide participants, The Boston Globe reports that Christopher’s only overseer was an uncertified 15-year-old gun enthusiast. Dr. Bizilj, the director of emergency medicine at a Connecticut hospital, was standing behind his son when the boy took aim at a pumpkin.

It would only worsen this tragedy, and perhaps spawn similar ones, if it were written off as an unfortunate accident.