On Tuesday, an 18-year-old gunman killed 19 children and two teachers at an elementary school in Uvalde, Texas. The massacre, inflicted on a group all huddled in one classroom, is now the country’s second-deadliest school shooting on record. The gunman had purchased two AR-15-style rifles in the week before carrying out Tuesday’s rampage, thanks in large part to the gun lobby’s vigorous push to allow gun sales to people under 21. Gov.