On the same day that a 24-year-old Kuwaiti-American named Mohammod Youssuf Abdulazeez apparently killed four Marines in Chattanooga, Tennessee, a jury in Colorado convicted James Holmes, now 27, of the murder of 12 people in an Aurora movie theater in July 2012. Such incidents are, sadly, not nearly uncommon enough. According to a USA Today tally, 387 people have been murdered in 78 mass killings since Holmes' attack on defenseless people trying to peacefully watch a Batman movie; 119 of the victims were children.
USA Today defines mass killings as those with at least four victims, not counting the attacker. One such attack has taken place about every two weeks in the U.S. since the newspaper began keeping track in 2006. The most recent number, 387, includes Thursday's Chattanooga killings — plus 14 other massing killings this year — and 63 or the 78 tallied mass killings involved guns, usually handguns. Read more about the grim numbers at USA Today.